* [PATCH V2 1/2] blk-mq: don't handle TAG_SHARED in restart
2017-10-27 4:43 [PATCH V2 0/2] block: remove unnecessary RESTART Ming Lei
@ 2017-10-27 4:43 ` Ming Lei
2017-10-27 4:43 ` [PATCH V2 2/2] blk-mq: don't restart queue when .get_budget returns BLK_STS_RESOURCE Ming Lei
` (2 subsequent siblings)
3 siblings, 0 replies; 43+ messages in thread
From: Ming Lei @ 2017-10-27 4:43 UTC (permalink / raw)
To: Jens Axboe, linux-block, Christoph Hellwig
Cc: Omar Sandoval, Bart Van Assche, Roman Pen, Hannes Reinecke, Ming Lei
Now restart is used in the following cases, and TAG_SHARED is for
SCSI only.
1) .get_budget() returns BLK_STS_RESOURCE
- if resource in target/host level isn't satisfied, this SCSI device
will be added in shost->starved_list, and the whole queue will be rerun
(via SCSI's built-in RESTART) in scsi_end_request() after any request
initiated from this host/targe is completed. Forget to mention, host level
resource can't be an issue for blk-mq at all.
- the same is true if resource in the queue level isn't satisfied.
- if there isn't outstanding request on this queue, then SCSI's RESTART
can't work(blk-mq's can't work too), and the queue will be run after
SCSI_QUEUE_DELAY, and finally all starved sdevs will be handled by SCSI's
RESTART when this request is finished
2) scsi_dispatch_cmd() returns BLK_STS_RESOURCE
- if there isn't onprogressing request on this queue, the queue
will be run after SCSI_QUEUE_DELAY
- otherwise, SCSI's RESTART covers the rerun.
3) blk_mq_get_driver_tag() failed
- BLK_MQ_S_TAG_WAITING covers the cross-queue RESTART for driver
allocation.
In one word, SCSI's built-in RESTART is enough to cover the queue
rerun, and we don't need to pay special attention to TAG_SHARED wrt. restart.
In my test on scsi_debug(8 luns), this patch improves IOPS by 20% ~ 30% when
running I/O on these 8 luns concurrently.
Aslo Roman Pen reported the current RESTART is very expensive especialy
when there are lots of LUNs attached in one host, such as in his
test, RESTART causes half of IOPS be cut.
Fixes: https://marc.info/?l=linux-kernel&m=150832216727524&w=2
Fixes: 6d8c6c0f97ad ("blk-mq: Restart a single queue if tag sets are shared")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq-sched.c | 78 +++-------------------------------------------------
1 file changed, 4 insertions(+), 74 deletions(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index df8581bb0a37..daab27feb653 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -68,25 +68,17 @@ static void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx)
set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
}
-static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
+void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
{
if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
- return false;
-
- if (hctx->flags & BLK_MQ_F_TAG_SHARED) {
- struct request_queue *q = hctx->queue;
+ return;
- if (test_and_clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
- atomic_dec(&q->shared_hctx_restart);
- } else
- clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
+ clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
if (blk_mq_hctx_has_pending(hctx)) {
blk_mq_run_hw_queue(hctx, true);
- return true;
+ return;
}
-
- return false;
}
/* return true if hctx need to run again */
@@ -385,68 +377,6 @@ static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
return true;
}
-/**
- * list_for_each_entry_rcu_rr - iterate in a round-robin fashion over rcu list
- * @pos: loop cursor.
- * @skip: the list element that will not be examined. Iteration starts at
- * @skip->next.
- * @head: head of the list to examine. This list must have at least one
- * element, namely @skip.
- * @member: name of the list_head structure within typeof(*pos).
- */
-#define list_for_each_entry_rcu_rr(pos, skip, head, member) \
- for ((pos) = (skip); \
- (pos = (pos)->member.next != (head) ? list_entry_rcu( \
- (pos)->member.next, typeof(*pos), member) : \
- list_entry_rcu((pos)->member.next->next, typeof(*pos), member)), \
- (pos) != (skip); )
-
-/*
- * Called after a driver tag has been freed to check whether a hctx needs to
- * be restarted. Restarts @hctx if its tag set is not shared. Restarts hardware
- * queues in a round-robin fashion if the tag set of @hctx is shared with other
- * hardware queues.
- */
-void blk_mq_sched_restart(struct blk_mq_hw_ctx *const hctx)
-{
- struct blk_mq_tags *const tags = hctx->tags;
- struct blk_mq_tag_set *const set = hctx->queue->tag_set;
- struct request_queue *const queue = hctx->queue, *q;
- struct blk_mq_hw_ctx *hctx2;
- unsigned int i, j;
-
- if (set->flags & BLK_MQ_F_TAG_SHARED) {
- /*
- * If this is 0, then we know that no hardware queues
- * have RESTART marked. We're done.
- */
- if (!atomic_read(&queue->shared_hctx_restart))
- return;
-
- rcu_read_lock();
- list_for_each_entry_rcu_rr(q, queue, &set->tag_list,
- tag_set_list) {
- queue_for_each_hw_ctx(q, hctx2, i)
- if (hctx2->tags == tags &&
- blk_mq_sched_restart_hctx(hctx2))
- goto done;
- }
- j = hctx->queue_num + 1;
- for (i = 0; i < queue->nr_hw_queues; i++, j++) {
- if (j == queue->nr_hw_queues)
- j = 0;
- hctx2 = queue->queue_hw_ctx[j];
- if (hctx2->tags == tags &&
- blk_mq_sched_restart_hctx(hctx2))
- break;
- }
-done:
- rcu_read_unlock();
- } else {
- blk_mq_sched_restart_hctx(hctx);
- }
-}
-
/*
* Add flush/fua to the queue. If we fail getting a driver tag, then
* punt to the requeue list. Requeue will re-invoke us from a context
--
2.9.5
^ permalink raw reply related [flat|nested] 43+ messages in thread* [PATCH V2 2/2] blk-mq: don't restart queue when .get_budget returns BLK_STS_RESOURCE
2017-10-27 4:43 [PATCH V2 0/2] block: remove unnecessary RESTART Ming Lei
2017-10-27 4:43 ` [PATCH V2 1/2] blk-mq: don't handle TAG_SHARED in restart Ming Lei
@ 2017-10-27 4:43 ` Ming Lei
2017-10-27 4:53 ` [PATCH V2 0/2] block: remove unnecessary RESTART Bart Van Assche
2017-10-31 20:29 ` Jens Axboe
3 siblings, 0 replies; 43+ messages in thread
From: Ming Lei @ 2017-10-27 4:43 UTC (permalink / raw)
To: Jens Axboe, linux-block, Christoph Hellwig
Cc: Omar Sandoval, Bart Van Assche, Roman Pen, Hannes Reinecke, Ming Lei
SCSI restarts its queue in scsi_end_request() automatically, so we don't
need to handle this case in blk-mq.
Especailly any request won't be dequeued in this case, we needn't to
worry about IO hang caused by restart vs. dispatch.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq-sched.c | 45 ++++++++++++++++++++-------------------------
block/blk-mq-sched.h | 2 +-
block/blk-mq.c | 8 ++------
3 files changed, 23 insertions(+), 32 deletions(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index daab27feb653..7775f6b12fa9 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -81,8 +81,12 @@ void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
}
}
-/* return true if hctx need to run again */
-static bool blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
+/*
+ * Only SCSI implements .get_budget and .put_budget, and SCSI restarts
+ * its queue by itself in its completion handler, so we don't need to
+ * restart queue if .get_budget() returns BLK_STS_NO_RESOURCE.
+ */
+static void blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
struct elevator_queue *e = q->elevator;
@@ -98,7 +102,7 @@ static bool blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
ret = blk_mq_get_dispatch_budget(hctx);
if (ret == BLK_STS_RESOURCE)
- return true;
+ break;
rq = e->type->ops.mq.dispatch_request(hctx);
if (!rq) {
@@ -116,8 +120,6 @@ static bool blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
*/
list_add(&rq->queuelist, &rq_list);
} while (blk_mq_dispatch_rq_list(q, &rq_list, true));
-
- return false;
}
static struct blk_mq_ctx *blk_mq_next_ctx(struct blk_mq_hw_ctx *hctx,
@@ -131,8 +133,12 @@ static struct blk_mq_ctx *blk_mq_next_ctx(struct blk_mq_hw_ctx *hctx,
return hctx->ctxs[idx];
}
-/* return true if hctx need to run again */
-static bool blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
+/*
+ * Only SCSI implements .get_budget and .put_budget, and SCSI restarts
+ * its queue by itself in its completion handler, so we don't need to
+ * restart queue if .get_budget() returns BLK_STS_NO_RESOURCE.
+ */
+static void blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
LIST_HEAD(rq_list);
@@ -147,7 +153,7 @@ static bool blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
ret = blk_mq_get_dispatch_budget(hctx);
if (ret == BLK_STS_RESOURCE)
- return true;
+ break;
rq = blk_mq_dequeue_from_ctx(hctx, ctx);
if (!rq) {
@@ -171,22 +177,19 @@ static bool blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
} while (blk_mq_dispatch_rq_list(q, &rq_list, true));
WRITE_ONCE(hctx->dispatch_from, ctx);
-
- return false;
}
/* return true if hw queue need to be run again */
-bool blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
+void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
struct elevator_queue *e = q->elevator;
const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
LIST_HEAD(rq_list);
- bool run_queue = false;
/* RCU or SRCU read lock is needed before checking quiesced flag */
if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)))
- return false;
+ return;
hctx->run++;
@@ -218,12 +221,12 @@ bool blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
blk_mq_sched_mark_restart_hctx(hctx);
if (blk_mq_dispatch_rq_list(q, &rq_list, false)) {
if (has_sched_dispatch)
- run_queue = blk_mq_do_dispatch_sched(hctx);
+ blk_mq_do_dispatch_sched(hctx);
else
- run_queue = blk_mq_do_dispatch_ctx(hctx);
+ blk_mq_do_dispatch_ctx(hctx);
}
} else if (has_sched_dispatch) {
- run_queue = blk_mq_do_dispatch_sched(hctx);
+ blk_mq_do_dispatch_sched(hctx);
} else if (q->mq_ops->get_budget) {
/*
* If we need to get budget before queuing request, we
@@ -233,19 +236,11 @@ bool blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
* TODO: get more budgets, and dequeue more requests in
* one time.
*/
- run_queue = blk_mq_do_dispatch_ctx(hctx);
+ blk_mq_do_dispatch_ctx(hctx);
} else {
blk_mq_flush_busy_ctxs(hctx, &rq_list);
blk_mq_dispatch_rq_list(q, &rq_list, false);
}
-
- if (run_queue && !blk_mq_sched_needs_restart(hctx) &&
- !test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state)) {
- blk_mq_sched_mark_restart_hctx(hctx);
- return true;
- }
-
- return false;
}
bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index 2434061cc5b7..9267d0b7c197 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -22,7 +22,7 @@ void blk_mq_sched_insert_requests(struct request_queue *q,
struct blk_mq_ctx *ctx,
struct list_head *list, bool run_queue_async);
-bool blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx);
+void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx);
int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e);
void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 097ca3ece716..e4d2490f4e7e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1226,7 +1226,6 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
{
int srcu_idx;
- bool run_queue;
/*
* We should be running this queue from one of the CPUs that
@@ -1243,18 +1242,15 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
rcu_read_lock();
- run_queue = blk_mq_sched_dispatch_requests(hctx);
+ blk_mq_sched_dispatch_requests(hctx);
rcu_read_unlock();
} else {
might_sleep();
srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
- run_queue = blk_mq_sched_dispatch_requests(hctx);
+ blk_mq_sched_dispatch_requests(hctx);
srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
}
-
- if (run_queue)
- blk_mq_run_hw_queue(hctx, true);
}
/*
--
2.9.5
^ permalink raw reply related [flat|nested] 43+ messages in thread* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-27 4:43 [PATCH V2 0/2] block: remove unnecessary RESTART Ming Lei
2017-10-27 4:43 ` [PATCH V2 1/2] blk-mq: don't handle TAG_SHARED in restart Ming Lei
2017-10-27 4:43 ` [PATCH V2 2/2] blk-mq: don't restart queue when .get_budget returns BLK_STS_RESOURCE Ming Lei
@ 2017-10-27 4:53 ` Bart Van Assche
2017-10-27 5:38 ` Ming Lei
2017-10-31 20:29 ` Jens Axboe
3 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-10-27 4:53 UTC (permalink / raw)
To: hch, linux-block, axboe, ming.lei
Cc: Bart Van Assche, roman.penyaev, osandov, hare
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YW1lbHkgdGhlIFNDU0kgY29yZT8NCg0KQmFydC4=
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-27 4:53 ` [PATCH V2 0/2] block: remove unnecessary RESTART Bart Van Assche
@ 2017-10-27 5:38 ` Ming Lei
2017-10-27 17:55 ` Roman Penyaev
2017-10-30 20:24 ` Bart Van Assche
0 siblings, 2 replies; 43+ messages in thread
From: Ming Lei @ 2017-10-27 5:38 UTC (permalink / raw)
To: Bart Van Assche; +Cc: hch, linux-block, axboe, roman.penyaev, osandov, hare
Hello Bart,
On Fri, Oct 27, 2017 at 04:53:18AM +0000, Bart Van Assche wrote:
> On Fri, 2017-10-27 at 12:43 +0800, Ming Lei wrote:
> > The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
> > by itself, and not necessary to waste CPU to do the expensive RESTART.
> > And Roman Pen reported that this RESTART cuts half of IOPS in his case.
> >
> > The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
> > and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
>
> Hello Ming,
>
> There are more block drivers than the SCSI core that share tags. If the
Could you share us what the other in-tree driver which share tags is?
If there are really more, and when all can share similar RESTART mechanism, I
think that is the time for considering the common RESTART.
> restart mechanism is removed from the blk-mq core, does that mean that all
> block drivers that share tags will have to follow the example of the SCSI
> core and implement a restart mechanism themselves? As far as I know there
If there are such drivers, there should have been their own restart mechanism
which works for long time before blk-mq comes, and more importantly each driver
has much more knowledge than generic block layer to handle the restart,
such as SCSI's restart, that means driver's implementation may be more efficient.
Also the RESTART for TAG-SHARED may never function as expected wrt. SCSI.
And more importantly the block's RESTART for TAG-SHARED has caused big performance
issue for people.
IMO, the above two reasons are enough to remove the current RESTART for shared-tag.
> is a strong preference in the Linux community to implement common mechanisms
> in the (block layer) core instead of in drivers. It seems to me like you are
> proposing the opposite, namely removing a general mechanism from the (block
> layer) core and moving it into a driver, namely the SCSI core?
Actually SCSI's RESTART is very thin, and it is just the per-host starved_list.
Thanks,
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-27 5:38 ` Ming Lei
@ 2017-10-27 17:55 ` Roman Penyaev
2017-10-28 15:47 ` Ming Lei
2017-10-30 20:33 ` Bart Van Assche
2017-10-30 20:24 ` Bart Van Assche
1 sibling, 2 replies; 43+ messages in thread
From: Roman Penyaev @ 2017-10-27 17:55 UTC (permalink / raw)
To: Ming Lei; +Cc: Bart Van Assche, hch, linux-block, axboe, osandov, hare
Hi Ming,
On Fri, Oct 27, 2017 at 7:38 AM, Ming Lei <ming.lei@redhat.com> wrote:
> Hello Bart,
>
> On Fri, Oct 27, 2017 at 04:53:18AM +0000, Bart Van Assche wrote:
>> On Fri, 2017-10-27 at 12:43 +0800, Ming Lei wrote:
>> > The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
>> > by itself, and not necessary to waste CPU to do the expensive RESTART.
>> > And Roman Pen reported that this RESTART cuts half of IOPS in his case.
>> >
>> > The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
>> > and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
>>
>> Hello Ming,
>>
>> There are more block drivers than the SCSI core that share tags. If the
>
> Could you share us what the other in-tree driver which share tags is?
>
> If there are really more, and when all can share similar RESTART mechanism, I
> think that is the time for considering the common RESTART.
>
>> restart mechanism is removed from the blk-mq core, does that mean that all
>> block drivers that share tags will have to follow the example of the SCSI
>> core and implement a restart mechanism themselves? As far as I know there
>
> If there are such drivers, there should have been their own restart mechanism
> which works for long time before blk-mq comes, and more importantly each driver
> has much more knowledge than generic block layer to handle the restart,
> such as SCSI's restart, that means driver's implementation may be more efficient.
Personally I would be happier if block layer would do restarts for me. My eyes
are bleeding when I see chunks of my own code which do this juggling with hctx,
enqueuing or dequeuing from a percpu lists, etc inside IBNBD driver.
> Also the RESTART for TAG-SHARED may never function as expected wrt. SCSI.
E.g. new BLK_MQ_F_NO_RESTARTS flag can help to disable restarts when they
are not needed.
> And more importantly the block's RESTART for TAG-SHARED has caused big performance
> issue for people.
That's just a bug in code, not a in issue with restarts, which can be fixed
if we put hctx which are needed to be restarted in percpu lists and avoid
long loops and contentions.
--
Roman
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-27 17:55 ` Roman Penyaev
@ 2017-10-28 15:47 ` Ming Lei
2017-10-30 20:33 ` Bart Van Assche
1 sibling, 0 replies; 43+ messages in thread
From: Ming Lei @ 2017-10-28 15:47 UTC (permalink / raw)
To: Roman Penyaev; +Cc: Bart Van Assche, hch, linux-block, axboe, osandov, hare
Hi Roman,
On Fri, Oct 27, 2017 at 07:55:33PM +0200, Roman Penyaev wrote:
> Hi Ming,
>
> On Fri, Oct 27, 2017 at 7:38 AM, Ming Lei <ming.lei@redhat.com> wrote:
> > Hello Bart,
> >
> > On Fri, Oct 27, 2017 at 04:53:18AM +0000, Bart Van Assche wrote:
> >> On Fri, 2017-10-27 at 12:43 +0800, Ming Lei wrote:
> >> > The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
> >> > by itself, and not necessary to waste CPU to do the expensive RESTART.
> >> > And Roman Pen reported that this RESTART cuts half of IOPS in his case.
> >> >
> >> > The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
> >> > and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
> >>
> >> Hello Ming,
> >>
> >> There are more block drivers than the SCSI core that share tags. If the
> >
> > Could you share us what the other in-tree driver which share tags is?
> >
> > If there are really more, and when all can share similar RESTART mechanism, I
> > think that is the time for considering the common RESTART.
> >
> >> restart mechanism is removed from the blk-mq core, does that mean that all
> >> block drivers that share tags will have to follow the example of the SCSI
> >> core and implement a restart mechanism themselves? As far as I know there
> >
> > If there are such drivers, there should have been their own restart mechanism
> > which works for long time before blk-mq comes, and more importantly each driver
> > has much more knowledge than generic block layer to handle the restart,
> > such as SCSI's restart, that means driver's implementation may be more efficient.
>
> Personally I would be happier if block layer would do restarts for me. My eyes
> are bleeding when I see chunks of my own code which do this juggling with hctx,
> enqueuing or dequeuing from a percpu lists, etc inside IBNBD driver.
The issue is that the current block's RESTART for TAG-SHARED isn't efficient, and
never functions as expected. And no one uses that at all actually.
Firstly we have handled cross-queue RESTART via BLK_MQ_S_TAG_WAITING already when
getting driver tag.
Secondly as you see, SCSI handles this kind of RESTART much more efficient and
simply via one linked list, I believe your IBNBD can do this in similar way,
right? If you can't figure out one easy way to do that, I am happy to
provide one patchset[1](which was done via sbitmap weeks ago) to do that
efficiently in block layer, but not the current approach, when you upstream your
IBNBD patchset.
https://github.com/ming1/linux/commits/blk_mq_improve_restart_V1-rc1
Finally you reported that the RESTART for TAG-SHARED has degraded your
IO performance by half, and that can't be accepted, IMO. I found the
similar performance issue in my test too.
>
> > Also the RESTART for TAG-SHARED may never function as expected wrt. SCSI.
>
> E.g. new BLK_MQ_F_NO_RESTARTS flag can help to disable restarts when they
> are not needed.
This flag is only needed iff there are more than one in-tree drivers which need
the RESTART for TAG-SHARED.
Also I have mentioned the current RESTART for TAG-SHARED has big performance issue.
>
> > And more importantly the block's RESTART for TAG-SHARED has caused big performance
> > issue for people.
>
> That's just a bug in code, not a in issue with restarts, which can be fixed
> if we put hctx which are needed to be restarted in percpu lists and avoid
> long loops and contentions.
Again no in-tree driver uses RESTART for TAG-SHARED now, so not necessary to fix
anything in the RESTART for TAG-SHARED.
If there is driver which need this kind of RESTART in future, one more efficient
implementation can be figured out at that time, but not now. As you see,
I already have one.
Thanks,
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-27 17:55 ` Roman Penyaev
2017-10-28 15:47 ` Ming Lei
@ 2017-10-30 20:33 ` Bart Van Assche
2017-11-01 16:55 ` Roman Penyaev
1 sibling, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-10-30 20:33 UTC (permalink / raw)
To: roman.penyaev, ming.lei; +Cc: hch, linux-block, osandov, axboe, hare
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^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-30 20:33 ` Bart Van Assche
@ 2017-11-01 16:55 ` Roman Penyaev
0 siblings, 0 replies; 43+ messages in thread
From: Roman Penyaev @ 2017-11-01 16:55 UTC (permalink / raw)
To: Bart Van Assche; +Cc: ming.lei, hch, linux-block, osandov, axboe, hare
On Mon, Oct 30, 2017 at 9:33 PM, Bart Van Assche <Bart.VanAssche@wdc.com> wrote:
> On Fri, 2017-10-27 at 19:55 +0200, Roman Penyaev wrote:
>> That's just a bug in code, not a in issue with restarts, which can be fixed
>> if we put hctx which are needed to be restarted in percpu lists and avoid
>> long loops and contentions.
>
> Hello Roman,
>
> Have you noticed that recently .get_budget() and .put_budget() callbacks have
> been added into struct blk_mq_ops? If block drivers that support shared tags
> implement these callback functions properly then maybe busy conditions become
> infrequent enough to use a single "hctx busy" list per tag set instead of
> per-cpu "hctx busy" lists.
Hi Bart,
No, not yet. Thanks, good tip.
--
Roman
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-27 5:38 ` Ming Lei
2017-10-27 17:55 ` Roman Penyaev
@ 2017-10-30 20:24 ` Bart Van Assche
2017-10-31 1:47 ` Ming Lei
1 sibling, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-10-30 20:24 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, axboe, hare
T24gRnJpLCAyMDE3LTEwLTI3IGF0IDEzOjM4ICswODAwLCBNaW5nIExlaSB3cm90ZToNCj4gT24g
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^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-30 20:24 ` Bart Van Assche
@ 2017-10-31 1:47 ` Ming Lei
2017-11-01 3:54 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-10-31 1:47 UTC (permalink / raw)
To: Bart Van Assche; +Cc: hch, roman.penyaev, linux-block, osandov, axboe, hare
On Mon, Oct 30, 2017 at 08:24:57PM +0000, Bart Van Assche wrote:
> On Fri, 2017-10-27 at 13:38 +0800, Ming Lei wrote:
> > On Fri, Oct 27, 2017 at 04:53:18AM +0000, Bart Van Assche wrote:
> > > On Fri, 2017-10-27 at 12:43 +0800, Ming Lei wrote:
> > > > The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
> > > > by itself, and not necessary to waste CPU to do the expensive RESTART.
> > > > And Roman Pen reported that this RESTART cuts half of IOPS in his case.
> > > >
> > > > The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
> > > > and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
> > >
> > > There are more block drivers than the SCSI core that share tags. If the
> >
> > Could you share us what the other in-tree driver which share tags is?
>
> I think the following in-tree drivers support shared tags (in alphabetical
> order):
> * null_blk. See also the shared_tags kernel module parameter.
> * nvme. See also nvme_alloc_ns().
For both null_blk and nvme, we don't need to deal with cross-queue RESTART,
because BLK_MQ_S_TAG_WAITING has handled it already.
> * scsi-mq.
>
> Please note that the queue_rq() function of *all* these drivers can return
> BLK_STS_RESOURCE.
Yes, but this patch doesn't remove the RESTART for the current hctx, and
only removed the part of handling cross-queue RESTART.
>
> > Actually SCSI's RESTART is very thin, and it is just the per-host starved_list.
>
> Do you see any reason that would prevent to move that mechanism from scsi-mq
> into the blk-mq core?
I don't see it is required from SCSI's view since this way has been run
for SCSI for long time, and we don't have this requirement for other
in-tree drivers meantime.
Also as I mentioned before, driver has more knowledge than generic block
layer for making it more efficiently.
Thanks,
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-31 1:47 ` Ming Lei
@ 2017-11-01 3:54 ` Bart Van Assche
2017-11-01 4:08 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-01 3:54 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, axboe, hare
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^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 3:54 ` Bart Van Assche
@ 2017-11-01 4:08 ` Ming Lei
2017-11-01 16:47 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-01 4:08 UTC (permalink / raw)
To: Bart Van Assche; +Cc: hch, roman.penyaev, linux-block, osandov, axboe, hare
On Wed, Nov 01, 2017 at 03:54:09AM +0000, Bart Van Assche wrote:
> On Tue, 2017-10-31 at 09:47 +0800, Ming Lei wrote:
> > On Mon, Oct 30, 2017 at 08:24:57PM +0000, Bart Van Assche wrote:
> > > On Fri, 2017-10-27 at 13:38 +0800, Ming Lei wrote:
> > > > On Fri, Oct 27, 2017 at 04:53:18AM +0000, Bart Van Assche wrote:
> > > > > On Fri, 2017-10-27 at 12:43 +0800, Ming Lei wrote:
> > > > > > The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
> > > > > > by itself, and not necessary to waste CPU to do the expensive RESTART.
> > > > > > And Roman Pen reported that this RESTART cuts half of IOPS in his case.
> > > > > >
> > > > > > The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
> > > > > > and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
> > > > >
> > > > > There are more block drivers than the SCSI core that share tags. If the
> > > >
> > > > Could you share us what the other in-tree driver which share tags is?
> > >
> > > I think the following in-tree drivers support shared tags (in alphabetical
> > > order):
> > > * null_blk. See also the shared_tags kernel module parameter.
> > > * nvme. See also nvme_alloc_ns().
> > > * scsi-mq.
> >
> > For both null_blk and nvme, we don't need to deal with cross-queue RESTART,
> > because BLK_MQ_S_TAG_WAITING has handled it already.
>
> blk_mq_dispatch_wait_add() returns immediately if BLK_MQ_S_TAG_WAITING is
> already set. Are you really sure that removing the restart mechanism doesn't
If this flag is set, that means blk_mq_dispatch_wake() will be run when
driver tag is available, so the hw queue will be run at that time.
> break the NVMe driver if there are multiple namespaces?
Did your commit 6d8c6c0f97ad ("blk-mq: Restart a single queue if tag sets are shared")
suppose to fix NVMe?
Please take a look at the cover letter:
https://marc.info/?t=149158911500010&r=1&w=2
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 4:08 ` Ming Lei
@ 2017-11-01 16:47 ` Bart Van Assche
2017-11-01 16:59 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-01 16:47 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, axboe, hare
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^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 16:47 ` Bart Van Assche
@ 2017-11-01 16:59 ` Ming Lei
2017-11-01 17:09 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-01 16:59 UTC (permalink / raw)
To: Bart Van Assche; +Cc: hch, roman.penyaev, linux-block, osandov, axboe, hare
On Wed, Nov 01, 2017 at 04:47:06PM +0000, Bart Van Assche wrote:
> On Wed, 2017-11-01 at 12:08 +0800, Ming Lei wrote:
> > On Wed, Nov 01, 2017 at 03:54:09AM +0000, Bart Van Assche wrote:
> > > On Tue, 2017-10-31 at 09:47 +0800, Ming Lei wrote:
> > > > On Mon, Oct 30, 2017 at 08:24:57PM +0000, Bart Van Assche wrote:
> > > > > On Fri, 2017-10-27 at 13:38 +0800, Ming Lei wrote:
> > > > > > On Fri, Oct 27, 2017 at 04:53:18AM +0000, Bart Van Assche wrote:
> > > > > > > On Fri, 2017-10-27 at 12:43 +0800, Ming Lei wrote:
> > > > > > > > The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
> > > > > > > > by itself, and not necessary to waste CPU to do the expensive RESTART.
> > > > > > > > And Roman Pen reported that this RESTART cuts half of IOPS in his case.
> > > > > > > >
> > > > > > > > The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
> > > > > > > > and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
> > > > > > >
> > > > > > > There are more block drivers than the SCSI core that share tags. If the
> > > > > >
> > > > > > Could you share us what the other in-tree driver which share tags is?
> > > > >
> > > > > I think the following in-tree drivers support shared tags (in alphabetical
> > > > > order):
> > > > > * null_blk. See also the shared_tags kernel module parameter.
> > > > > * nvme. See also nvme_alloc_ns().
> > > > > * scsi-mq.
> > > >
> > > > For both null_blk and nvme, we don't need to deal with cross-queue RESTART,
> > > > because BLK_MQ_S_TAG_WAITING has handled it already.
> > >
> > > blk_mq_dispatch_wait_add() returns immediately if BLK_MQ_S_TAG_WAITING is
> > > already set. Are you really sure that removing the restart mechanism doesn't
> > > break the NVMe driver if there are multiple namespaces?>
> > If this flag is set, that means blk_mq_dispatch_wake() will be run when
> > driver tag is available, so the hw queue will be run at that time.
>
> The only hw queue that will be rerun if BLK_MQ_S_TAG_WAITING is set is the hw
> queue for which that flag was set. Sorry but I don't think that mechanism by
> itself is sufficient to avoid queue lockups with the NVMe driver in case of
> shared namespaces. See also the description of commit da55f2cc7841 ("blk-mq:
Why?
> use sbq wait queues instead of restart for driver tags").
This commit just make sure that the hctx of BLK_MQ_S_TAG_WAITING will be
run again once there is driver tag available, see its commit log simply:
However, we can still use the struct sbitmap_queue wait queues with a
custom callback instead of blocking. This has a few benefits:
1. It avoids iterating over all hardware queues when completing an I/O,
which the current restart code has to do.
2. It benefits from the existing rolling wakeup code.
3. It avoids punting to another thread just to have it block.
The commit has described clearly that we don't need to iterate over all hw
queue when completing an I/O.
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 16:59 ` Ming Lei
@ 2017-11-01 17:09 ` Bart Van Assche
2017-11-01 17:22 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-01 17:09 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, axboe, hare
T24gVGh1LCAyMDE3LTExLTAyIGF0IDAwOjU5ICswODAwLCBNaW5nIExlaSB3cm90ZToNCj4gVGhl
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YWJvdmUgaXMgbm90IGNvcnJlY3QuDQoNCkJhcnQu
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 17:09 ` Bart Van Assche
@ 2017-11-01 17:22 ` Ming Lei
0 siblings, 0 replies; 43+ messages in thread
From: Ming Lei @ 2017-11-01 17:22 UTC (permalink / raw)
To: Bart Van Assche; +Cc: hch, roman.penyaev, linux-block, osandov, axboe, hare
On Wed, Nov 01, 2017 at 05:09:41PM +0000, Bart Van Assche wrote:
> On Thu, 2017-11-02 at 00:59 +0800, Ming Lei wrote:
> > The commit has described clearly that we don't need to iterate over all hw
> > queue when completing an I/O.
>
> You quoted a small part of the description of commit da55f2cc7841 and left out
> the part that shows that what you wrote above is not correct.
If you mean the 1st part:
Commit 50e1dab86aa2 ("blk-mq-sched: fix starvation for multiple hardware
queues and shared tags") fixed one starvation issue for shared tags.
However, we can still get into a situation where we fail to allocate a
tag because all tags are allocated but we don't have any pending
requests on any hardware queue.
That is just what this commit wants to address, then we don't need to
depend on restart from all hctx for fixing this starvation.
If you don't believe me, you can ask Omar and Jens to clarify.
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-27 4:43 [PATCH V2 0/2] block: remove unnecessary RESTART Ming Lei
` (2 preceding siblings ...)
2017-10-27 4:53 ` [PATCH V2 0/2] block: remove unnecessary RESTART Bart Van Assche
@ 2017-10-31 20:29 ` Jens Axboe
2017-11-01 1:46 ` Ming Lei
3 siblings, 1 reply; 43+ messages in thread
From: Jens Axboe @ 2017-10-31 20:29 UTC (permalink / raw)
To: Ming Lei, linux-block, Christoph Hellwig
Cc: Omar Sandoval, Bart Van Assche, Roman Pen, Hannes Reinecke
On 10/26/2017 10:43 PM, Ming Lei wrote:
> Hi Jens,
>
> The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
> by itself, and not necessary to waste CPU to do the expensive RESTART.
> And Roman Pen reported that this RESTART cuts half of IOPS in his case.
>
> The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
> and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
What base is this against?
--
Jens Axboe
^ permalink raw reply [flat|nested] 43+ messages in thread* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-10-31 20:29 ` Jens Axboe
@ 2017-11-01 1:46 ` Ming Lei
2017-11-01 1:53 ` Jens Axboe
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-01 1:46 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-block, Christoph Hellwig, Omar Sandoval, Bart Van Assche,
Roman Pen, Hannes Reinecke
On Tue, Oct 31, 2017 at 02:29:32PM -0600, Jens Axboe wrote:
> On 10/26/2017 10:43 PM, Ming Lei wrote:
> > Hi Jens,
> >
> > The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
> > by itself, and not necessary to waste CPU to do the expensive RESTART.
> > And Roman Pen reported that this RESTART cuts half of IOPS in his case.
> >
> > The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
> > and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
>
> What base is this against?
The for-next branch of your block tree:
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 1:46 ` Ming Lei
@ 2017-11-01 1:53 ` Jens Axboe
2017-11-01 2:03 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Jens Axboe @ 2017-11-01 1:53 UTC (permalink / raw)
To: Ming Lei
Cc: linux-block, Christoph Hellwig, Omar Sandoval, Bart Van Assche,
Roman Pen, Hannes Reinecke
> On Oct 31, 2017, at 7:46 PM, Ming Lei <ming.lei@redhat.com> wrote:
>=20
>> On Tue, Oct 31, 2017 at 02:29:32PM -0600, Jens Axboe wrote:
>>> On 10/26/2017 10:43 PM, Ming Lei wrote:
>>> Hi Jens,
>>>=20
>>> The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it=
>>> by itself, and not necessary to waste CPU to do the expensive RESTART.
>>> And Roman Pen reported that this RESTART cuts half of IOPS in his case.
>>>=20
>>> The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOU=
RCE,
>>> and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
>>=20
>> What base is this against?
>=20
> The for-next branch of your block tree:
=46rom when? Doesn=E2=80=99t apply at all today.=20
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 1:53 ` Jens Axboe
@ 2017-11-01 2:03 ` Ming Lei
2017-11-01 14:21 ` Jens Axboe
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-01 2:03 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-block, Christoph Hellwig, Omar Sandoval, Bart Van Assche,
Roman Pen, Hannes Reinecke
On Tue, Oct 31, 2017 at 07:53:03PM -0600, Jens Axboe wrote:
>
> > On Oct 31, 2017, at 7:46 PM, Ming Lei <ming.lei@redhat.com> wrote:
> >
> >> On Tue, Oct 31, 2017 at 02:29:32PM -0600, Jens Axboe wrote:
> >>> On 10/26/2017 10:43 PM, Ming Lei wrote:
> >>> Hi Jens,
> >>>
> >>> The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
> >>> by itself, and not necessary to waste CPU to do the expensive RESTART.
> >>> And Roman Pen reported that this RESTART cuts half of IOPS in his case.
> >>>
> >>> The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
> >>> and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
> >>
> >> What base is this against?
> >
> > The for-next branch of your block tree:
>
> From when? Doesn’t apply at all today.
I just tried today's for-next(top commit is 'MAINTAINERS: Remove Rafael from Opal maintainers.'),
and the two patches can be applied cleanly.
I guess you may try to apply the two patches against for-4.15/block,
which doesn't include the patchset of '[PATCH V10 0/8] blk-mq-sched: improve sequential I/O'[1]:
https://marc.info/?t=150797316600002&r=1&w=2
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 2:03 ` Ming Lei
@ 2017-11-01 14:21 ` Jens Axboe
2017-11-02 15:57 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Jens Axboe @ 2017-11-01 14:21 UTC (permalink / raw)
To: Ming Lei
Cc: linux-block, Christoph Hellwig, Omar Sandoval, Bart Van Assche,
Roman Pen, Hannes Reinecke
On 10/31/2017 08:03 PM, Ming Lei wrote:
> On Tue, Oct 31, 2017 at 07:53:03PM -0600, Jens Axboe wrote:
>>
>>> On Oct 31, 2017, at 7:46 PM, Ming Lei <ming.lei@redhat.com> wrote:
>>>
>>>> On Tue, Oct 31, 2017 at 02:29:32PM -0600, Jens Axboe wrote:
>>>>> On 10/26/2017 10:43 PM, Ming Lei wrote:
>>>>> Hi Jens,
>>>>>
>>>>> The 1st patch removes the RESTART for TAG-SHARED because SCSI handles it
>>>>> by itself, and not necessary to waste CPU to do the expensive RESTART.
>>>>> And Roman Pen reported that this RESTART cuts half of IOPS in his case.
>>>>>
>>>>> The 2nd patch removes the RESTART when .get_budget returns BLK_STS_RESOURCE,
>>>>> and this RESTART is handled by SCSI's RESTART(scsi_end_request()) too.
>>>>
>>>> What base is this against?
>>>
>>> The for-next branch of your block tree:
>>
>> From when? Doesn’t apply at all today.
>
> I just tried today's for-next(top commit is 'MAINTAINERS: Remove Rafael from Opal maintainers.'),
> and the two patches can be applied cleanly.
>
> I guess you may try to apply the two patches against for-4.15/block,
> which doesn't include the patchset of '[PATCH V10 0/8] blk-mq-sched: improve sequential I/O'[1]:
>
> https://marc.info/?t=150797316600002&r=1&w=2
I'm the idiot, for some reason that patchset got applied to for-next
directly. That's not supposed to happen, for-next is always just
a merge point. Fixed that up, and applied these two patches as
well.
--
Jens Axboe
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-01 14:21 ` Jens Axboe
@ 2017-11-02 15:57 ` Bart Van Assche
2017-11-02 23:38 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-02 15:57 UTC (permalink / raw)
To: axboe, ming.lei
Cc: Bart Van Assche, hch, roman.penyaev, linux-block, osandov, hare
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^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-02 15:57 ` Bart Van Assche
@ 2017-11-02 23:38 ` Ming Lei
2017-11-02 23:43 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-02 23:38 UTC (permalink / raw)
To: Bart Van Assche; +Cc: axboe, hch, roman.penyaev, linux-block, osandov, hare
On Thu, Nov 02, 2017 at 03:57:05PM +0000, Bart Van Assche wrote:
> On Wed, 2017-11-01 at 08:21 -0600, Jens Axboe wrote:
> > Fixed that up, and applied these two patches as well.
>
> Hello Jens,
>
> Recently I noticed that a test system sporadically hangs during boot (Dell
> PowerEdge R720 that boots from a hard disk connected to a MegaRAID SAS adapter)
> and also that srp-tests systematically hangs. Reverting the two patches from
> this series fixes both issues. I'm not sure there is another solution than
> reverting the two patches from this series.
Then we need to find the root cause, instead of using sort of workaround
as before.
For SCSI, the restart is always run from scsi_end_request(), and this
kind of restart from all hctx isn't necessary at all.
>
> Bart.
>
>
> BTW, the following appeared in the kernel log when I tried to run srp-tests
> against a kernel with the two patches from this series applied:
>
> INFO: task kworker/19:1:209 blocked for more than 480 seconds.
> INFO: task kworker/19:1:209 blocked for more than 480 seconds.
> Tainted: G W 4.14.0-rc7-dbg+ #1
> Tainted: G W 4.14.0-rc7-dbg+ #1
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> kworker/19:1 D 0 209 2 0x80000000
> kworker/19:1 D 0 209 2 0x80000000
> Workqueue: srp_remove srp_remove_work [ib_srp]
> Workqueue: srp_remove srp_remove_work [ib_srp]
> Call Trace:
> Call Trace:
> __schedule+0x2fa/0xbb0
> __schedule+0x2fa/0xbb0
> schedule+0x36/0x90
> schedule+0x36/0x90
> async_synchronize_cookie_domain+0x88/0x130
> async_synchronize_cookie_domain+0x88/0x130
> ? finish_wait+0x90/0x90
> ? finish_wait+0x90/0x90
> async_synchronize_full_domain+0x18/0x20
> async_synchronize_full_domain+0x18/0x20
> sd_remove+0x4d/0xc0 [sd_mod]
> sd_remove+0x4d/0xc0 [sd_mod]
> device_release_driver_internal+0x160/0x210
> device_release_driver_internal+0x160/0x210
> device_release_driver+0x12/0x20
> device_release_driver+0x12/0x20
> bus_remove_device+0x100/0x180
> bus_remove_device+0x100/0x180
> device_del+0x1d8/0x340
> device_del+0x1d8/0x340
> __scsi_remove_device+0xfc/0x130
> __scsi_remove_device+0xfc/0x130
> scsi_forget_host+0x25/0x70
> scsi_forget_host+0x25/0x70
> scsi_remove_host+0x79/0x120
> scsi_remove_host+0x79/0x120
> srp_remove_work+0x90/0x1d0 [ib_srp]
> srp_remove_work+0x90/0x1d0 [ib_srp]
> process_one_work+0x20a/0x660
> process_one_work+0x20a/0x660
> worker_thread+0x3d/0x3b0
> worker_thread+0x3d/0x3b0
> kthread+0x13a/0x150
> kthread+0x13a/0x150
> ? process_one_work+0x660/0x660
> ? process_one_work+0x660/0x660
> ? kthread_create_on_node+0x40/0x40
> ? kthread_create_on_node+0x40/0x40
> ret_from_fork+0x27/0x40
> ret_from_fork+0x27/0x40
>
> Showing all locks held in the system:
>
> Showing all locks held in the system:
> 1 lock held by khungtaskd/170:
> 1 lock held by khungtaskd/170:
> #0: (tasklist_lock){.+.+}, at: [<ffffffff810c125d>] debug_show_all_locks+0x3d/0x1a0
> #0: (tasklist_lock){.+.+}, at: [<ffffffff810c125d>] debug_show_all_locks+0x3d/0x1a0
> 4 locks held by kworker/19:1/209:
> 4 locks held by kworker/19:1/209:
> #0: ("%s"("srp_remove")){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #0: ("%s"("srp_remove")){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&target->remove_work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&target->remove_work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #2: (&shost->scan_mutex){+.+.}, at: [<ffffffff814807bf>] scsi_remove_host+0x1f/0x120
> #2: (&shost->scan_mutex){+.+.}, at: [<ffffffff814807bf>] scsi_remove_host+0x1f/0x120
> #3: (&dev->mutex){....}, at: [<ffffffff814501a9>] device_release_driver_internal+0x39/0x210
> #3: (&dev->mutex){....}, at: [<ffffffff814501a9>] device_release_driver_internal+0x39/0x210
> 2 locks held by kworker/u66:0/1927:
> 2 locks held by kworker/u66:0/1927:
> #0: ("events_unbound"){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #0: ("events_unbound"){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&entry->work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&entry->work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> 2 locks held by kworker/5:0/2047:
> 2 locks held by kworker/5:0/2047:
> #0: ("kaluad"){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #0: ("kaluad"){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&(&pg->rtpg_work)->work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&(&pg->rtpg_work)->work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
>
>
> =============================================
>
> =============================================
>
> INFO: task kworker/19:1:209 blocked for more than 480 seconds.
> INFO: task kworker/19:1:209 blocked for more than 480 seconds.
> Tainted: G W 4.14.0-rc7-dbg+ #1
> Tainted: G W 4.14.0-rc7-dbg+ #1
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> kworker/19:1 D 0 209 2 0x80000000
> kworker/19:1 D 0 209 2 0x80000000
> Workqueue: srp_remove srp_remove_work [ib_srp]
> Workqueue: srp_remove srp_remove_work [ib_srp]
> Call Trace:
> Call Trace:
> __schedule+0x2fa/0xbb0
> __schedule+0x2fa/0xbb0
> schedule+0x36/0x90
> schedule+0x36/0x90
> async_synchronize_cookie_domain+0x88/0x130
> async_synchronize_cookie_domain+0x88/0x130
> ? finish_wait+0x90/0x90
> ? finish_wait+0x90/0x90
> async_synchronize_full_domain+0x18/0x20
> async_synchronize_full_domain+0x18/0x20
> sd_remove+0x4d/0xc0 [sd_mod]
> sd_remove+0x4d/0xc0 [sd_mod]
> device_release_driver_internal+0x160/0x210
> device_release_driver_internal+0x160/0x210
> device_release_driver+0x12/0x20
> device_release_driver+0x12/0x20
> bus_remove_device+0x100/0x180
> bus_remove_device+0x100/0x180
> device_del+0x1d8/0x340
> device_del+0x1d8/0x340
> __scsi_remove_device+0xfc/0x130
> __scsi_remove_device+0xfc/0x130
> scsi_forget_host+0x25/0x70
> scsi_forget_host+0x25/0x70
> scsi_remove_host+0x79/0x120
> scsi_remove_host+0x79/0x120
> srp_remove_work+0x90/0x1d0 [ib_srp]
> srp_remove_work+0x90/0x1d0 [ib_srp]
> process_one_work+0x20a/0x660
> process_one_work+0x20a/0x660
> worker_thread+0x3d/0x3b0
> worker_thread+0x3d/0x3b0
> kthread+0x13a/0x150
> kthread+0x13a/0x150
> ? process_one_work+0x660/0x660
> ? process_one_work+0x660/0x660
> ? kthread_create_on_node+0x40/0x40
> ? kthread_create_on_node+0x40/0x40
> ret_from_fork+0x27/0x40
> ret_from_fork+0x27/0x40
>
> Showing all locks held in the system:
>
> Showing all locks held in the system:
> 1 lock held by khungtaskd/170:
> 1 lock held by khungtaskd/170:
> #0: (tasklist_lock){.+.+}, at: [<ffffffff810c125d>] debug_show_all_locks+0x3d/0x1a0
> #0: (tasklist_lock){.+.+}, at: [<ffffffff810c125d>] debug_show_all_locks+0x3d/0x1a0
> 4 locks held by kworker/19:1/209:
> 4 locks held by kworker/19:1/209:
> #0: ("%s"("srp_remove")){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #0: ("%s"("srp_remove")){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&target->remove_work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&target->remove_work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #2: (&shost->scan_mutex){+.+.}, at: [<ffffffff814807bf>] scsi_remove_host+0x1f/0x120
> #2: (&shost->scan_mutex){+.+.}, at: [<ffffffff814807bf>] scsi_remove_host+0x1f/0x120
> #3: (&dev->mutex){....}, at: [<ffffffff814501a9>] device_release_driver_internal+0x39/0x210
> #3: (&dev->mutex){....}, at: [<ffffffff814501a9>] device_release_driver_internal+0x39/0x210
> 2 locks held by kworker/u66:0/1927:
> 2 locks held by kworker/u66:0/1927:
> #0: ("events_unbound"){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #0: ("events_unbound"){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&entry->work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&entry->work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> 2 locks held by kworker/5:0/2047:
> 2 locks held by kworker/5:0/2047:
> #0: ("kaluad"){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #0: ("kaluad"){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&(&pg->rtpg_work)->work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
> #1: ((&(&pg->rtpg_work)->work)){+.+.}, at: [<ffffffff81083b85>] process_one_work+0x195/0x660
>
>
> =============================================
>
> =============================================
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-02 23:38 ` Ming Lei
@ 2017-11-02 23:43 ` Bart Van Assche
2017-11-02 23:48 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-02 23:43 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, hare, axboe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^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-02 23:43 ` Bart Van Assche
@ 2017-11-02 23:48 ` Ming Lei
2017-11-02 23:54 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-02 23:48 UTC (permalink / raw)
To: Bart Van Assche; +Cc: hch, roman.penyaev, linux-block, osandov, hare, axboe
On Thu, Nov 02, 2017 at 11:43:55PM +0000, Bart Van Assche wrote:
> On Fri, 2017-11-03 at 07:38 +0800, Ming Lei wrote:
> > On Thu, Nov 02, 2017 at 03:57:05PM +0000, Bart Van Assche wrote:
> > > On Wed, 2017-11-01 at 08:21 -0600, Jens Axboe wrote:
> > > > Fixed that up, and applied these two patches as well.
> > >
> > > Hello Jens,
> > >
> > > Recently I noticed that a test system sporadically hangs during boot (Dell
> > > PowerEdge R720 that boots from a hard disk connected to a MegaRAID SAS adapter)
> > > and also that srp-tests systematically hangs. Reverting the two patches from
> > > this series fixes both issues. I'm not sure there is another solution than
> > > reverting the two patches from this series.
> >
> > Then we need to find the root cause, instead of using sort of workaround
> > as before.
> >
> > For SCSI, the restart is always run from scsi_end_request(), and this
> > kind of restart from all hctx isn't necessary at all.
>
> Yes, we need to find the root cause, but after these two patches have either
> been reverted or have been removed from the for-4.15 queue. Otherwise if a
> bisect lands in the middle of these two patches and the fix for these patches
> that would be very frustrating for the person who is running the bisect.
Could you please share your srp-tests script? I may find a IB/SRP system
to see if I can reproduce this issue and figure out one solution.
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-02 23:48 ` Ming Lei
@ 2017-11-02 23:54 ` Bart Van Assche
2017-11-03 0:15 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-02 23:54 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, hare, axboe
T24gRnJpLCAyMDE3LTExLTAzIGF0IDA3OjQ4ICswODAwLCBNaW5nIExlaSB3cm90ZToNCj4gQ291
bGQgeW91IHBsZWFzZSBzaGFyZSB5b3VyIHNycC10ZXN0cyBzY3JpcHQ/IEkgbWF5IGZpbmQgYSBJ
Qi9TUlAgc3lzdGVtDQo+IHRvIHNlZSBpZiBJIGNhbiByZXByb2R1Y2UgdGhpcyBpc3N1ZSBhbmQg
ZmlndXJlIG91dCBvbmUgc29sdXRpb24uDQoNClBsZWFzZSBoYXZlIGEgbG9vayBhdCBodHRwczov
L2dpdGh1Yi5jb20vYnZhbmFzc2NoZS9zcnAtdGVzdC4NCg0KQmFydC4=
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-02 23:54 ` Bart Van Assche
@ 2017-11-03 0:15 ` Ming Lei
2017-11-03 0:48 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-03 0:15 UTC (permalink / raw)
To: Bart Van Assche; +Cc: hch, roman.penyaev, linux-block, osandov, hare, axboe
On Thu, Nov 02, 2017 at 11:54:57PM +0000, Bart Van Assche wrote:
> On Fri, 2017-11-03 at 07:48 +0800, Ming Lei wrote:
> > Could you please share your srp-tests script? I may find a IB/SRP system
> > to see if I can reproduce this issue and figure out one solution.
>
> Please have a look at https://github.com/bvanassche/srp-test.
Could you provide me the exact command line for the reproduction?
I simply run ./run_tests, and looks it doesn't work.
[root@ srp-test]# ./run_tests
df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
Unmounting /home/ming/git/srp-test/mnt2 from
umount: /home/ming/git/srp-test/mnt2: mountpoint not found
df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
Error: unmounting /home/ming/git/srp-test/mnt2 failed
Thanks,
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 0:15 ` Ming Lei
@ 2017-11-03 0:48 ` Bart Van Assche
2017-11-03 1:16 ` Laurence Oberman
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-03 0:48 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, hare, axboe
T24gRnJpLCAyMDE3LTExLTAzIGF0IDA4OjE1ICswODAwLCBNaW5nIExlaSB3cm90ZToNCj4gT24g
VGh1LCBOb3YgMDIsIDIwMTcgYXQgMTE6NTQ6NTdQTSArMDAwMCwgQmFydCBWYW4gQXNzY2hlIHdy
b3RlOg0KPiA+IE9uIEZyaSwgMjAxNy0xMS0wMyBhdCAwNzo0OCArMDgwMCwgTWluZyBMZWkgd3Jv
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SSBtYXkgZmluZCBhIElCL1NSUCBzeXN0ZW0NCj4gPiA+IHRvIHNlZSBpZiBJIGNhbiByZXByb2R1
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dGhlIHJlcHJvZHVjdGlvbj8NCj4gDQo+IEkgc2ltcGx5IHJ1biAuL3J1bl90ZXN0cywgYW5kIGxv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==
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 0:48 ` Bart Van Assche
@ 2017-11-03 1:16 ` Laurence Oberman
2017-11-03 2:12 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Laurence Oberman @ 2017-11-03 1:16 UTC (permalink / raw)
To: Bart Van Assche
Cc: Ming Lei, Hellwig, Christoph, roman.penyaev, linux-block,
osandov, Reinecke, Hannes, Jens Axboe
[-- Attachment #1: Type: text/plain, Size: 1331 bytes --]
Hi Ming
I have used Bart's tests on my test bed they should run fine.
Are you using my SRP setup.
Thanks
Laurence
On Nov 2, 2017 8:48 PM, "Bart Van Assche" <Bart.VanAssche@wdc.com> wrote:
> On Fri, 2017-11-03 at 08:15 +0800, Ming Lei wrote:
> > On Thu, Nov 02, 2017 at 11:54:57PM +0000, Bart Van Assche wrote:
> > > On Fri, 2017-11-03 at 07:48 +0800, Ming Lei wrote:
> > > > Could you please share your srp-tests script? I may find a IB/SRP
> system
> > > > to see if I can reproduce this issue and figure out one solution.
> > >
> > > Please have a look at https://github.com/bvanassche/srp-test.
> >
> > Could you provide me the exact command line for the reproduction?
> >
> > I simply run ./run_tests, and looks it doesn't work.
> >
> > [root@ srp-test]# ./run_tests
> > df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
> > df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
> > Unmounting /home/ming/git/srp-test/mnt2 from
> > umount: /home/ming/git/srp-test/mnt2: mountpoint not found
> > df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
> > Error: unmounting /home/ming/git/srp-test/mnt2 failed
>
> This means that I have to add the following to the README document:
>
> Run "mkdir mnt1 mnt2 mnt3" before starting the tests.
>
> Bart.
[-- Attachment #2: Type: text/html, Size: 1984 bytes --]
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 1:16 ` Laurence Oberman
@ 2017-11-03 2:12 ` Ming Lei
2017-11-03 2:42 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-03 2:12 UTC (permalink / raw)
To: Laurence Oberman
Cc: Bart Van Assche, Hellwig, Christoph, roman.penyaev, linux-block,
osandov, Reinecke, Hannes, Jens Axboe
Hi Laurence,
On Thu, Nov 02, 2017 at 09:16:04PM -0400, Laurence Oberman wrote:
> Hi Ming
> I have used Bart's tests on my test bed they should run fine.
> Are you using my SRP setup.
Yeah, I am using your SRP setup.
Once the three directories are created, I saw the new failure,
and both ib/srp and dm-mpath has been working well now.
Laurence and Bart, do you have receipt for making the test
working first?
[root@ibclient srp-test]# ./run_tests
modprobe: FATAL: Module target_core_mod is in use.
[root@ibclient srp-test]# lsmod | grep target
iscsi_target_mod 294912 1 ib_isert
target_core_mod 352256 2 iscsi_target_mod,ib_isert
[root@ibclient srp-test]# lsblk | head -n 10
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sdy 65:128 0 3.9G 0 disk
└─36001405b2b5c6c24c084b6fa4d55da2f 253:16 0 3.9G 0 mpath
sdam 66:96 0 3.9G 0 disk
└─360014055f563ebf2abc4609a00a16794 253:11 0 3.9G 0 mpath
sdbb 67:80 0 3.9G 0 disk
└─36001405f58163b828714988bd2e88358 253:17 0 3.9G 0 mpath
sdf 8:80 0 3.9G 0 disk
└─36001405fb1402260c1346688f23d07e0 253:7 0 3.9G 0 mpath
sdau 66:224 0 3.9G 0 disk
Thanks,
Ming
>
> Thanks
> Laurence
>
>
> On Nov 2, 2017 8:48 PM, "Bart Van Assche" <Bart.VanAssche@wdc.com> wrote:
>
> > On Fri, 2017-11-03 at 08:15 +0800, Ming Lei wrote:
> > > On Thu, Nov 02, 2017 at 11:54:57PM +0000, Bart Van Assche wrote:
> > > > On Fri, 2017-11-03 at 07:48 +0800, Ming Lei wrote:
> > > > > Could you please share your srp-tests script? I may find a IB/SRP
> > system
> > > > > to see if I can reproduce this issue and figure out one solution.
> > > >
> > > > Please have a look at https://github.com/bvanassche/srp-test.
> > >
> > > Could you provide me the exact command line for the reproduction?
> > >
> > > I simply run ./run_tests, and looks it doesn't work.
> > >
> > > [root@ srp-test]# ./run_tests
> > > df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
> > > df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
> > > Unmounting /home/ming/git/srp-test/mnt2 from
> > > umount: /home/ming/git/srp-test/mnt2: mountpoint not found
> > > df: ‘/home/ming/git/srp-test/mnt2’: No such file or directory
> > > Error: unmounting /home/ming/git/srp-test/mnt2 failed
> >
> > This means that I have to add the following to the README document:
> >
> > Run "mkdir mnt1 mnt2 mnt3" before starting the tests.
> >
> > Bart.
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 2:12 ` Ming Lei
@ 2017-11-03 2:42 ` Bart Van Assche
2017-11-03 3:50 ` Ming Lei
2017-11-03 15:18 ` Ming Lei
0 siblings, 2 replies; 43+ messages in thread
From: Bart Van Assche @ 2017-11-03 2:42 UTC (permalink / raw)
To: ming.lei, loberman; +Cc: hch, roman.penyaev, linux-block, osandov, hare, axboe
T24gRnJpLCAyMDE3LTExLTAzIGF0IDEwOjEyICswODAwLCBNaW5nIExlaSB3cm90ZToNCj4gW3Jv
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ZWZvcmUgc3JwLXRlc3Qgc29mdHdhcmUgaXMgc3RhcnRlZC4NCg0KQmFydC4=
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 2:42 ` Bart Van Assche
@ 2017-11-03 3:50 ` Ming Lei
2017-11-03 15:23 ` Bart Van Assche
2017-11-03 15:18 ` Ming Lei
1 sibling, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-03 3:50 UTC (permalink / raw)
To: Bart Van Assche
Cc: loberman, hch, roman.penyaev, linux-block, osandov, hare, axboe
On Fri, Nov 03, 2017 at 02:42:50AM +0000, Bart Van Assche wrote:
> On Fri, 2017-11-03 at 10:12 +0800, Ming Lei wrote:
> > [root@ibclient srp-test]# ./run_tests
> > modprobe: FATAL: Module target_core_mod is in use.
>
> LIO must be unloaded before srp-test software is started.
Yeah, I can make this test kick off after running
'modprobe -fr ib_isert' first, but looks all tests failed without
any hang, could you check if that is the expected result?
https://pastebin.com/VXe66Jpg
Also could you provide some output from debugfs when this hang happens?
such as:
dispatch/busy/.. under hctxN
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 3:50 ` Ming Lei
@ 2017-11-03 15:23 ` Bart Van Assche
2017-11-03 15:47 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-03 15:23 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, hare, loberman, axboe
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OS45MTA3OTddIFJJUDogMDAzMzoweDdmNWRjNGUzMmQxMQ0KWyAgNzA5LjkxNTkxN10gUlNQOiAw
MDJiOjAwMDA3ZmZlYjBiMTA1ODggRUZMQUdTOiAwMDAwMDI0NiBPUklHX1JBWDogMDAwMDAwMDAw
MDAwMDAwMA0KWyAgNzA5LjkyNTU4OV0gUkFYOiBmZmZmZmZmZmZmZmZmZmZjIFJCWDogMDAwMDU2
MjMwZGE4NDQ5MCBSQ1g6IDAwMDA3ZjVkYzRlMzJkMTENClsgIDcwOS45MzQ3ODVdIFJEWDogMDAw
MDAwMDAwMDAwMDA0MCBSU0k6IDAwMDA1NjIzMGRhODQ0YjggUkRJOiAwMDAwMDAwMDAwMDAwMDA3
DQpbICA3MDkuOTQzOTg3XSBSQlA6IDAwMDA1NjIzMGRhYmMzYzAgUjA4OiAwMDAwMDAwMDAwMDAw
MDAwIFIwOTogMDAwMDU2MjMwZGE4NDQ5MA0KWyAgNzA5Ljk1MzIwMl0gUjEwOiAwMDAwMDAwMDAw
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OiAwMDAwMDAwMDAwMDAwMDQwDQo=
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 15:23 ` Bart Van Assche
@ 2017-11-03 15:47 ` Ming Lei
2017-11-03 15:50 ` Bart Van Assche
0 siblings, 1 reply; 43+ messages in thread
From: Ming Lei @ 2017-11-03 15:47 UTC (permalink / raw)
To: Bart Van Assche
Cc: hch, roman.penyaev, linux-block, osandov, hare, loberman, axboe
On Fri, Nov 03, 2017 at 03:23:14PM +0000, Bart Van Assche wrote:
> On Fri, 2017-11-03 at 11:50 +0800, Ming Lei wrote:
> > On Fri, Nov 03, 2017 at 02:42:50AM +0000, Bart Van Assche wrote:
> > > On Fri, 2017-11-03 at 10:12 +0800, Ming Lei wrote:
> > > > [root@ibclient srp-test]# ./run_tests
> > > > modprobe: FATAL: Module target_core_mod is in use.
> > >
> > > LIO must be unloaded before srp-test software is started.
> >
> > Yeah, I can make this test kick off after running
> > 'modprobe -fr ib_isert' first, but looks all tests failed without
> > any hang, could you check if that is the expected result?
> >
> > https://pastebin.com/VXe66Jpg
>
> I see plenty of "... >/sys/.../add_target failed: Connection timed out"
> messages. The srp-test scripts use the loopback functionality of IB ports
> so one or more IB ports must be active. Have you already checked the IB
> ports state, e.g. by running ibv_devinfo?
[root@ibclient ~]# ibv_devinfo
hca_id: mlx5_1
transport: InfiniBand (0)
fw_ver: 12.20.1010
node_guid: 7cfe:9003:0072:6ed3
sys_image_guid: 7cfe:9003:0072:6ed2
vendor_id: 0x02c9
vendor_part_id: 4115
hw_ver: 0x0
board_id: MT_2190110032
phys_port_cnt: 1
port: 1
state: PORT_ACTIVE (4)
max_mtu: 4096 (5)
active_mtu: 4096 (5)
sm_lid: 1
port_lid: 1
port_lmc: 0x00
link_layer: InfiniBand
hca_id: mlx5_0
transport: InfiniBand (0)
fw_ver: 12.20.1010
node_guid: 7cfe:9003:0072:6ed2
sys_image_guid: 7cfe:9003:0072:6ed2
vendor_id: 0x02c9
vendor_part_id: 4115
hw_ver: 0x0
board_id: MT_2190110032
phys_port_cnt: 1
port: 1
state: PORT_ACTIVE (4)
max_mtu: 4096 (5)
active_mtu: 4096 (5)
sm_lid: 4
port_lid: 4
port_lmc: 0x00
link_layer: InfiniBand
Forget to mention, there is failure when running 'make' under srp-test
because shellcheck package is missed in RHEL7. Can that be the issue
of test failure? If yes, could you provide a special version of srp-test
which doesn't depend on shellcheck?
>
> > Also could you provide some output from debugfs when this hang happens?
> > such as:
> >
> > dispatch/busy/.. under hctxN
>
> This is the output that appears on my test setup if the two patches from
> the patch series "block: remove unnecessary RESTART" are applied:
>
> # ~bart/software/infiniband/srp-test/run_tests -f xfs -d -e deadline -r 60
> Unloaded the ib_srpt kernel module
> Zero-initializing /dev/ram0 ... done
> Zero-initializing /dev/ram1 ... done
> Zero-initializing /dev/disk/by-id/scsi-33333333000004650 ... done
> brw-rw---- 1 root disk 1, 0 Nov 3 08:10 /dev/ram0
> /dev/ram0
> brw-rw---- 1 root disk 1, 1 Nov 3 08:10 /dev/ram1
> /dev/ram1
> lrwxrwxrwx 1 root root 9 Nov 3 08:11 /dev/disk/by-id/scsi-33333333000004650 -> ../../sdi
> /dev/sdi
> Configured SRP target driver
> Running test /home/bart/software/infiniband/srp-test/tests/01 ...
> id_ext=0x0002c90300a02d50,ioc_guid=0x0002c90300a02d50,dgid=fe800000000000000002c90300a02d51,pkey=7fff,service_id=0x0002c90300a02d50, >/sys/class/infiniband_srp/
> srp-mlx4_0-2/add_target failed: Invalid argument
> id_ext=0x0002c90300a02d50,ioc_guid=0x0002c90300a02d50,dgid=fe800000000000000002c90300a02d52,pkey=7fff,service_id=0x0002c90300a02d50, >/sys/class/infiniband_srp/
> srp-mlx4_0-2/add_target failed: Invalid argument
> count_luns(): 3 <> 3
> Error: unloading kernel module ib_srp failed
> Test /home/bart/software/infiniband/srp-test/tests/01 failed
> # cat /sys/module/scsi_mod/parameters/use_blk_mq
> Y
> # find /sys/kernel/debug/block -name busy | xargs cat
Can you check 'dispatch' file, hctx state, tags and sched_tags?
And see where is the IO not dispatched?
> # dmesg -c >/dev/null; echo w > /proc/sysrq-trigger; dmesg
> [ 709.321750] sysrq: SysRq : Show Blocked State
> [ 709.327906] task PC stack pid father
...
> [ 709.456602] kworker/u66:6 D 0 341 2 0x80000000
> [ 709.463371] Workqueue: events_unbound async_run_entry_fn
> [ 709.469919] Call Trace:
> [ 709.473325] __schedule+0x2fa/0xbb0
> [ 709.477850] ? trace_hardirqs_on_caller+0xfb/0x190
> [ 709.483847] schedule+0x36/0x90
> [ 709.487982] schedule_timeout+0x22c/0x570
> [ 709.493115] ? call_timer_fn+0x330/0x330
> [ 709.498133] ? wait_for_completion_io_timeout+0xf7/0x180
> [ 709.504732] io_schedule_timeout+0x1e/0x50
> [ 709.509938] ? io_schedule_timeout+0x1e/0x50
> [ 709.515413] wait_for_completion_io_timeout+0x11f/0x180
> [ 709.521920] ? wake_up_q+0x80/0x80
> [ 709.526376] blk_execute_rq+0x86/0xc0
> [ 709.531135] scsi_execute+0xdb/0x1f0
> [ 709.536336] sd_revalidate_disk+0xed/0x1c70 [sd_mod]
> [ 709.543281] sd_probe_async+0xc3/0x1d0 [sd_mod]
> [ 709.549524] async_run_entry_fn+0x38/0x160
> [ 709.555503] process_one_work+0x20a/0x660
> [ 709.561299] worker_thread+0x3d/0x3b0
> [ 709.566688] kthread+0x13a/0x150
> [ 709.571613] ? process_one_work+0x660/0x660
> [ 709.577561] ? kthread_create_on_node+0x40/0x40
> [ 709.583910] ret_from_fork+0x27/0x40
Looks hang in scsi_execute().
> [ 709.589174] kworker/5:2 D 0 386 2 0x80000000
> [ 709.596616] Workqueue: kaluad alua_rtpg_work [scsi_dh_alua]
> [ 709.604130] Call Trace:
> [ 709.608096] __schedule+0x2fa/0xbb0
> [ 709.613265] ? trace_hardirqs_on_caller+0xfb/0x190
> [ 709.619879] schedule+0x36/0x90
> [ 709.624684] schedule_timeout+0x22c/0x570
> [ 709.630437] ? call_timer_fn+0x330/0x330
> [ 709.636059] ? wait_for_completion_io_timeout+0xf7/0x180
> [ 709.643270] io_schedule_timeout+0x1e/0x50
> [ 709.649083] ? io_schedule_timeout+0x1e/0x50
> [ 709.655159] wait_for_completion_io_timeout+0x11f/0x180
> [ 709.662284] ? wake_up_q+0x80/0x80
> [ 709.667334] blk_execute_rq+0x86/0xc0
> [ 709.672705] scsi_execute+0xdb/0x1f0
> [ 709.677938] alua_rtpg_work+0x2b3/0xe8a [scsi_dh_alua]
> [ 709.684983] process_one_work+0x20a/0x660
> [ 709.690759] worker_thread+0x3d/0x3b0
> [ 709.696107] kthread+0x13a/0x150
> [ 709.700986] ? process_one_work+0x660/0x660
> [ 709.706920] ? kthread_create_on_node+0x40/0x40
> [ 709.713316] ret_from_fork+0x27/0x40
Same with above.
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 15:47 ` Ming Lei
@ 2017-11-03 15:50 ` Bart Van Assche
2017-11-03 16:13 ` Laurence Oberman
0 siblings, 1 reply; 43+ messages in thread
From: Bart Van Assche @ 2017-11-03 15:50 UTC (permalink / raw)
To: ming.lei; +Cc: axboe, hch, roman.penyaev, linux-block, osandov, hare, loberman
T24gRnJpLCAyMDE3LTExLTAzIGF0IDIzOjQ3ICswODAwLCBNaW5nIExlaSB3cm90ZToNCj4gRm9y
Z2V0IHRvIG1lbnRpb24sIHRoZXJlIGlzIGZhaWx1cmUgd2hlbiBydW5uaW5nICdtYWtlJyB1bmRl
ciBzcnAtdGVzdA0KPiBiZWNhdXNlIHNoZWxsY2hlY2sgcGFja2FnZSBpcyBtaXNzZWQgaW4gUkhF
TDcuIENhbiB0aGF0IGJlIHRoZSBpc3N1ZQ0KPiBvZiB0ZXN0IGZhaWx1cmU/IElmIHllcywgY291
bGQgeW91IHByb3ZpZGUgYSBzcGVjaWFsIHZlcnNpb24gb2Ygc3JwLXRlc3QNCj4gd2hpY2ggZG9l
c24ndCBkZXBlbmQgb24gc2hlbGxjaGVjaz8NCg0KVGhlIHNycC10ZXN0IHNvZnR3YXJlIGRvZXMg
bm90IGRlcGVuZCBvbiBzaGVsbGNoZWNrLiBUaGUgb25seSBwdXJwb3NlIG9mDQp0aGUgInNoZWxs
Y2hlY2siIHRhcmdldCBpbiB0aGUgc3JwLXRlc3QgTWFrZWZpbGUgaXMgdG8gdmVyaWZ5IHRoZSBz
eW50YXgNCm9mIHRoZSBzaGVsbCBzY3JpcHRzLiBUaGUgdGVzdHMgcnVuIGZpbmUgZXZlbiBpZiBz
aGVsbGNoZWNrIGlzIG1pc3NpbmcuDQoNCkJhcnQu
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 15:50 ` Bart Van Assche
@ 2017-11-03 16:13 ` Laurence Oberman
2017-11-03 16:47 ` Ming Lei
0 siblings, 1 reply; 43+ messages in thread
From: Laurence Oberman @ 2017-11-03 16:13 UTC (permalink / raw)
To: Bart Van Assche
Cc: Ming Lei, Jens Axboe, hch, roman.penyaev, linux-block, osandov, hare
[-- Attachment #1: Type: text/plain, Size: 779 bytes --]
Hi
I had it working some time back. I am off today to take my son to the
doctor.
I will get Bart's test working again this weekend.
Thanks
Laurence
On Nov 3, 2017 11:51 AM, "Bart Van Assche" <Bart.VanAssche@wdc.com> wrote:
> On Fri, 2017-11-03 at 23:47 +0800, Ming Lei wrote:
> > Forget to mention, there is failure when running 'make' under srp-test
> > because shellcheck package is missed in RHEL7. Can that be the issue
> > of test failure? If yes, could you provide a special version of srp-test
> > which doesn't depend on shellcheck?
>
> The srp-test software does not depend on shellcheck. The only purpose of
> the "shellcheck" target in the srp-test Makefile is to verify the syntax
> of the shell scripts. The tests run fine even if shellcheck is missing.
>
> Bart.
[-- Attachment #2: Type: text/html, Size: 1214 bytes --]
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 16:13 ` Laurence Oberman
@ 2017-11-03 16:47 ` Ming Lei
2017-11-03 17:13 ` Laurence Oberman
2017-11-04 2:11 ` Ming Lei
0 siblings, 2 replies; 43+ messages in thread
From: Ming Lei @ 2017-11-03 16:47 UTC (permalink / raw)
To: Laurence Oberman
Cc: Bart Van Assche, Jens Axboe, hch, roman.penyaev, linux-block,
osandov, hare
On Fri, Nov 03, 2017 at 12:13:09PM -0400, Laurence Oberman wrote:
> Hi
> I had it working some time back. I am off today to take my son to the
> doctor.
> I will get Bart's test working again this weekend.
Hello Laurence and Bart,
Just found srp-test starts to work now with v4.14-rc4 kernel, and
the IO hang issue has been reproduced one time. BTW, the connection
failure happened on for-next of block tree.
Will investigate the issue this weekend.
Thanks,
Ming
>
> On Nov 3, 2017 11:51 AM, "Bart Van Assche" <Bart.VanAssche@wdc.com> wrote:
>
> > On Fri, 2017-11-03 at 23:47 +0800, Ming Lei wrote:
> > > Forget to mention, there is failure when running 'make' under srp-test
> > > because shellcheck package is missed in RHEL7. Can that be the issue
> > > of test failure? If yes, could you provide a special version of srp-test
> > > which doesn't depend on shellcheck?
> >
> > The srp-test software does not depend on shellcheck. The only purpose of
> > the "shellcheck" target in the srp-test Makefile is to verify the syntax
> > of the shell scripts. The tests run fine even if shellcheck is missing.
> >
> > Bart.
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 16:47 ` Ming Lei
@ 2017-11-03 17:13 ` Laurence Oberman
2017-11-04 2:11 ` Ming Lei
1 sibling, 0 replies; 43+ messages in thread
From: Laurence Oberman @ 2017-11-03 17:13 UTC (permalink / raw)
To: Ming Lei
Cc: Bart Van Assche, Jens Axboe, hch, roman.penyaev, linux-block,
osandov, hare
[-- Attachment #1: Type: text/plain, Size: 1473 bytes --]
Hi Ming
OK.
However that newer test kernel this morning (not rc4) has issues. Even with
device discovery.
Let me know if you want me to work on it after you are done this weekend.
Thanks
Laurence
On Nov 3, 2017 12:47 PM, "Ming Lei" <ming.lei@redhat.com> wrote:
> On Fri, Nov 03, 2017 at 12:13:09PM -0400, Laurence Oberman wrote:
> > Hi
> > I had it working some time back. I am off today to take my son to the
> > doctor.
> > I will get Bart's test working again this weekend.
>
> Hello Laurence and Bart,
>
> Just found srp-test starts to work now with v4.14-rc4 kernel, and
> the IO hang issue has been reproduced one time. BTW, the connection
> failure happened on for-next of block tree.
>
> Will investigate the issue this weekend.
>
> Thanks,
> Ming
>
> >
> > On Nov 3, 2017 11:51 AM, "Bart Van Assche" <Bart.VanAssche@wdc.com>
> wrote:
> >
> > > On Fri, 2017-11-03 at 23:47 +0800, Ming Lei wrote:
> > > > Forget to mention, there is failure when running 'make' under
> srp-test
> > > > because shellcheck package is missed in RHEL7. Can that be the issue
> > > > of test failure? If yes, could you provide a special version of
> srp-test
> > > > which doesn't depend on shellcheck?
> > >
> > > The srp-test software does not depend on shellcheck. The only purpose
> of
> > > the "shellcheck" target in the srp-test Makefile is to verify the
> syntax
> > > of the shell scripts. The tests run fine even if shellcheck is missing.
> > >
> > > Bart.
>
> --
> Ming
>
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^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 16:47 ` Ming Lei
2017-11-03 17:13 ` Laurence Oberman
@ 2017-11-04 2:11 ` Ming Lei
1 sibling, 0 replies; 43+ messages in thread
From: Ming Lei @ 2017-11-04 2:11 UTC (permalink / raw)
To: Laurence Oberman
Cc: Bart Van Assche, Jens Axboe, hch, roman.penyaev, linux-block,
osandov, hare
On Sat, Nov 04, 2017 at 12:47:31AM +0800, Ming Lei wrote:
> On Fri, Nov 03, 2017 at 12:13:09PM -0400, Laurence Oberman wrote:
> > Hi
> > I had it working some time back. I am off today to take my son to the
> > doctor.
> > I will get Bart's test working again this weekend.
>
> Hello Laurence and Bart,
>
> Just found srp-test starts to work now with v4.14-rc4 kernel, and
> the IO hang issue has been reproduced one time. BTW, the connection
> failure happened on for-next of block tree.
>
> Will investigate the issue this weekend.
Hi Bart,
Please test the following patch to see if your issue can be fixed:
https://marc.info/?l=linux-scsi&m=150976056219162&w=2
I run three times of your test 01, not see the hang issue any more
once this patch is applied.
Thanks,
Ming
>
> >
> > On Nov 3, 2017 11:51 AM, "Bart Van Assche" <Bart.VanAssche@wdc.com> wrote:
> >
> > > On Fri, 2017-11-03 at 23:47 +0800, Ming Lei wrote:
> > > > Forget to mention, there is failure when running 'make' under srp-test
> > > > because shellcheck package is missed in RHEL7. Can that be the issue
> > > > of test failure? If yes, could you provide a special version of srp-test
> > > > which doesn't depend on shellcheck?
> > >
> > > The srp-test software does not depend on shellcheck. The only purpose of
> > > the "shellcheck" target in the srp-test Makefile is to verify the syntax
> > > of the shell scripts. The tests run fine even if shellcheck is missing.
> > >
> > > Bart.
>
> --
> Ming
--
Ming
^ permalink raw reply [flat|nested] 43+ messages in thread
* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 2:42 ` Bart Van Assche
2017-11-03 3:50 ` Ming Lei
@ 2017-11-03 15:18 ` Ming Lei
2017-11-03 15:43 ` Bart Van Assche
2017-11-03 15:47 ` Bart Van Assche
1 sibling, 2 replies; 43+ messages in thread
From: Ming Lei @ 2017-11-03 15:18 UTC (permalink / raw)
To: Bart Van Assche
Cc: loberman, hch, roman.penyaev, linux-block, osandov, hare, axboe
On Fri, Nov 03, 2017 at 02:42:50AM +0000, Bart Van Assche wrote:
> On Fri, 2017-11-03 at 10:12 +0800, Ming Lei wrote:
> > [root@ibclient srp-test]# ./run_tests
> > modprobe: FATAL: Module target_core_mod is in use.
>
> LIO must be unloaded before srp-test software is started.
Hi Bart,
Even with help of Laurence, we still can't setup your srp-test
in our test environment today.
But we have run Laurence's usual 3 tests on IB/SRP with/without all
my following patches against V4.14-rc4, looks everything is fine, and
no I/O hang is observed.
0001-blk-mq-sched-dispatch-from-scheduler-IFF-progress-is.patch
0002-blk-mq-sched-move-actual-dispatching-into-one-helper.patch
0003-sbitmap-introduce-__sbitmap_for_each_set.patch
0004-block-kyber-check-if-there-are-requests-in-ctx-in-ky.patch
0005-blk-mq-introduce-.get_budget-and-.put_budget-in-blk_.patch
0006-blk-mq-sched-improve-dispatching-from-sw-queue.patch
0007-scsi-allow-passing-in-null-rq-to-scsi_prep_state_che.patch
0008-scsi-implement-.get_budget-and-.put_budget-for-blk-m.patch
0009-blk-mq-don-t-handle-TAG_SHARED-in-restart.patch
0010-blk-mq-don-t-restart-queue-when-.get_budget-returns-.patch
BTW, Laurence found there is kernel crash in his IB/SRP test when running
for-next branch of block tree, so we just test v4.14-rc4 w/wo my blk-mq patches.
And I looked at the SCSI's queue_rq code for a while, and only found
one issue which may cause IO hang, and the following patch may address
this issue, but not sure if it is same with your issue. Could you apply
this patch and see if your issue can be fixed?
BTW, it should be helpful to check the blk-mq debugfs related files
when your I/O hang happens, could you provide that info?
--
>From edcb243d9a6f3446bd9a9f95c00bed7616dd7368 Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@redhat.com>
Date: Fri, 3 Nov 2017 12:11:59 +0800
Subject: [PATCH] SCSI_MQ: fix IO hang in case of queue busy
We have to insert the rq back before checking .device_busy,
otherwise When IO completes just after the check and before
this req is added to hctx->dispatch, this queue may never get
chance to be run, then this IO may hang forever.
This patch introduces BLK_STS_RESOURCE_OK for handling this
issue.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq.c | 17 +++++++++++++++++
drivers/scsi/scsi_lib.c | 8 ++++++++
include/linux/blk-mq.h | 1 +
include/linux/blk_types.h | 1 +
4 files changed, 27 insertions(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index e4d2490f4e7e..e1e03576edca 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -660,6 +660,16 @@ static void __blk_mq_requeue_request(struct request *rq)
}
}
+void blk_mq_reinsert_request_hctx(struct blk_mq_hw_ctx *hctx, struct request *rq)
+{
+ __blk_mq_requeue_request(rq);
+
+ spin_lock(&hctx->lock);
+ list_add_tail(&rq->queuelist, &hctx->dispatch);
+ spin_unlock(&hctx->lock);
+}
+EXPORT_SYMBOL(blk_mq_reinsert_request_hctx);
+
void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
{
__blk_mq_requeue_request(rq);
@@ -1165,6 +1175,12 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
list_add(&rq->queuelist, list);
__blk_mq_requeue_request(rq);
break;
+ } else if (ret == BLK_STS_RESOURCE_OK) {
+ /*
+ * BLK_STS_RESOURCE_OK means driver handled this
+ * STS_RESOURCE already, we just need to stop dispatch.
+ */
+ break;
}
fail_rq:
@@ -1656,6 +1672,7 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
ret = q->mq_ops->queue_rq(hctx, &bd);
switch (ret) {
case BLK_STS_OK:
+ case BLK_STS_RESOURCE_OK:
*cookie = new_cookie;
return;
case BLK_STS_RESOURCE:
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 7f218ef61900..0165c1caed82 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2030,9 +2030,17 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
case BLK_STS_OK:
break;
case BLK_STS_RESOURCE:
+ /*
+ * We have to insert the rq back before checking .device_busy,
+ * otherwise when IO completes just after the check and before
+ * this req is added to hctx->dispatch, this queue may never get
+ * chance to be run, then this IO may hang forever.
+ */
+ blk_mq_reinsert_request_hctx(hctx, req);
if (atomic_read(&sdev->device_busy) == 0 &&
!scsi_device_blocked(sdev))
blk_mq_delay_run_hw_queue(hctx, SCSI_QUEUE_DELAY);
+ ret = BLK_STS_RESOURCE_OK;
break;
default:
/*
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index e5e6becd57d3..4740f643d8c5 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -244,6 +244,7 @@ void blk_mq_start_request(struct request *rq);
void blk_mq_end_request(struct request *rq, blk_status_t error);
void __blk_mq_end_request(struct request *rq, blk_status_t error);
+void blk_mq_reinsert_request_hctx(struct blk_mq_hw_ctx *hctx, struct request *rq);
void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list);
void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
bool kick_requeue_list);
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 3385c89f402e..b630cc026a93 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -32,6 +32,7 @@ typedef u8 __bitwise blk_status_t;
#define BLK_STS_PROTECTION ((__force blk_status_t)8)
#define BLK_STS_RESOURCE ((__force blk_status_t)9)
#define BLK_STS_IOERR ((__force blk_status_t)10)
+#define BLK_STS_RESOURCE_OK ((__force blk_status_t)11)
/* hack for device mapper, don't use elsewhere: */
#define BLK_STS_DM_REQUEUE ((__force blk_status_t)11)
--
2.9.5
--
Ming
^ permalink raw reply related [flat|nested] 43+ messages in thread* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 15:18 ` Ming Lei
@ 2017-11-03 15:43 ` Bart Van Assche
2017-11-03 15:47 ` Bart Van Assche
1 sibling, 0 replies; 43+ messages in thread
From: Bart Van Assche @ 2017-11-03 15:43 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, hare, loberman, axboe
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* Re: [PATCH V2 0/2] block: remove unnecessary RESTART
2017-11-03 15:18 ` Ming Lei
2017-11-03 15:43 ` Bart Van Assche
@ 2017-11-03 15:47 ` Bart Van Assche
1 sibling, 0 replies; 43+ messages in thread
From: Bart Van Assche @ 2017-11-03 15:47 UTC (permalink / raw)
To: ming.lei; +Cc: hch, roman.penyaev, linux-block, osandov, hare, loberman, axboe
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^ permalink raw reply [flat|nested] 43+ messages in thread