From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>,
John Garry <john.garry@huawei.com>,
Bart Van Assche <bvanassche@acm.org>,
Hannes Reinecke <hare@suse.com>, Christoph Hellwig <hch@lst.de>,
Thomas Gleixner <tglx@linutronix.de>,
Keith Busch <keith.busch@intel.com>
Subject: [PATCH V3 3/5] blk-mq: stop to handle IO and drain IO before hctx becomes dead
Date: Tue, 8 Oct 2019 12:18:19 +0800 [thread overview]
Message-ID: <20191008041821.2782-4-ming.lei@redhat.com> (raw)
In-Reply-To: <20191008041821.2782-1-ming.lei@redhat.com>
Before one CPU becomes offline, check if it is the last online CPU
of hctx. If yes, mark this hctx as BLK_MQ_S_INTERNAL_STOPPED, meantime
wait for completion of all in-flight IOs originated from this hctx.
This way guarantees that there isn't any inflight IO before shutdowning
the managed IRQ line.
Cc: John Garry <john.garry@huawei.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Keith Busch <keith.busch@intel.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq-tag.c | 2 +-
block/blk-mq-tag.h | 2 ++
block/blk-mq.c | 40 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 008388e82b5c..31828b82552b 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -325,7 +325,7 @@ static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt,
* true to continue iterating tags, false to stop.
* @priv: Will be passed as second argument to @fn.
*/
-static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags,
+void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags,
busy_tag_iter_fn *fn, void *priv)
{
if (tags->nr_reserved_tags)
diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h
index 61deab0b5a5a..321fd6f440e6 100644
--- a/block/blk-mq-tag.h
+++ b/block/blk-mq-tag.h
@@ -35,6 +35,8 @@ extern int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
extern void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool);
void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn,
void *priv);
+void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags,
+ busy_tag_iter_fn *fn, void *priv);
static inline struct sbq_wait_state *bt_wait_ptr(struct sbitmap_queue *bt,
struct blk_mq_hw_ctx *hctx)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index a664f196782a..3384242202eb 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2225,8 +2225,46 @@ int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
return -ENOMEM;
}
+static bool blk_mq_count_inflight_rq(struct request *rq, void *data,
+ bool reserved)
+{
+ unsigned *count = data;
+
+ if ((blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT))
+ (*count)++;
+
+ return true;
+}
+
+static unsigned blk_mq_tags_inflight_rqs(struct blk_mq_tags *tags)
+{
+ unsigned count = 0;
+
+ blk_mq_all_tag_busy_iter(tags, blk_mq_count_inflight_rq, &count);
+
+ return count;
+}
+
+static void blk_mq_hctx_drain_inflight_rqs(struct blk_mq_hw_ctx *hctx)
+{
+ while (1) {
+ if (!blk_mq_tags_inflight_rqs(hctx->tags))
+ break;
+ msleep(5);
+ }
+}
+
static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node)
{
+ struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
+ struct blk_mq_hw_ctx, cpuhp_online);
+
+ if ((cpumask_next_and(-1, hctx->cpumask, cpu_online_mask) == cpu) &&
+ (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) >=
+ nr_cpu_ids)) {
+ set_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state);
+ blk_mq_hctx_drain_inflight_rqs(hctx);
+ }
return 0;
}
@@ -2246,6 +2284,8 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
ctx = __blk_mq_get_ctx(hctx->queue, cpu);
type = hctx->type;
+ clear_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state);
+
spin_lock(&ctx->lock);
if (!list_empty(&ctx->rq_lists[type])) {
list_splice_init(&ctx->rq_lists[type], &tmp);
--
2.20.1
next prev parent reply other threads:[~2019-10-08 4:18 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-08 4:18 [PATCH V3 0/5] blk-mq: improvement on handling IO during CPU hotplug Ming Lei
2019-10-08 4:18 ` [PATCH V3 1/5] blk-mq: add new state of BLK_MQ_S_INTERNAL_STOPPED Ming Lei
2019-10-08 4:18 ` [PATCH V3 2/5] blk-mq: prepare for draining IO when hctx's all CPUs are offline Ming Lei
2019-10-08 4:18 ` Ming Lei [this message]
2019-10-08 17:03 ` [PATCH V3 3/5] blk-mq: stop to handle IO and drain IO before hctx becomes dead John Garry
2019-10-08 4:18 ` [PATCH V3 4/5] blk-mq: re-submit IO in case that hctx is dead Ming Lei
2019-10-08 4:18 ` [PATCH V3 5/5] blk-mq: handle requests dispatched from IO scheduler " Ming Lei
2019-10-08 9:06 ` [PATCH V3 0/5] blk-mq: improvement on handling IO during CPU hotplug John Garry
2019-10-08 17:15 ` John Garry
2019-10-09 8:39 ` Ming Lei
2019-10-09 8:49 ` John Garry
2019-10-10 10:30 ` Ming Lei
2019-10-10 11:21 ` John Garry
2019-10-11 8:51 ` John Garry
2019-10-11 11:55 ` Ming Lei
2019-10-11 14:10 ` John Garry
2019-10-14 1:25 ` Ming Lei
2019-10-14 8:29 ` John Garry
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