[PATCH for-next 0/4] Misc update for RNBD

[PATCH for-next 0/4] Misc update for RNBD

[Gioh Kim]

Some misc updates for RNBD:
* Remove unnecessary likely/unlikely macro from if-else statement
* Fix coding style issues reported by checkpatch.pl
* Add error check

Dima Stepanov (1):
  block/rnbd: Fix style issues

Gioh Kim (1):
  block/rnbd: Remove all likely and unlikely

Md Haris Iqbal (2):
  block/rnbd-clt: Change queue_depth type in rnbd_clt_session to size_t
  block/rnbd-clt: Check the return value of the function rtrs_clt_query

 drivers/block/rnbd/rnbd-clt.c | 46 ++++++++++++++++++++---------------
 drivers/block/rnbd/rnbd-clt.h |  2 +-
 drivers/block/rnbd/rnbd-srv.c |  2 +-
 3 files changed, 29 insertions(+), 21 deletions(-)

-- 
2.25.1

[PATCH for-next 1/4] block/rnbd-clt: Change queue_depth type in rnbd_clt_session to size_t

[Gioh Kim]

From: Md Haris Iqbal <haris.iqbal@cloud.ionos.com>

The member queue_depth in the structure rnbd_clt_session is read from the
rtrs client side using the function rtrs_clt_query, which in turn is read
from the rtrs_clt structure. It should really be of type size_t.

Fixes: 90426e89f54db ("block/rnbd: client: private header with client structs and functions")
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Reviewed-by: Guoqing Jiang <guoqing.jiang@ionos.com>
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
---
 drivers/block/rnbd/rnbd-clt.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/rnbd/rnbd-clt.h b/drivers/block/rnbd/rnbd-clt.h
index 451e7383738f..b5322c5aaac0 100644
--- a/drivers/block/rnbd/rnbd-clt.h
+++ b/drivers/block/rnbd/rnbd-clt.h
@@ -87,7 +87,7 @@ struct rnbd_clt_session {
 	DECLARE_BITMAP(cpu_queues_bm, NR_CPUS);
 	int	__percpu	*cpu_rr; /* per-cpu var for CPU round-robin */
 	atomic_t		busy;
-	int			queue_depth;
+	size_t			queue_depth;
 	u32			max_io_size;
 	struct blk_mq_tag_set	tag_set;
 	u32			nr_poll_queues;
-- 
2.25.1

Re: [PATCH for-next 1/4] block/rnbd-clt: Change queue_depth type in rnbd_clt_session to size_t

[Chaitanya Kulkarni]

On 4/27/21 23:14, Gioh Kim wrote:
> From: Md Haris Iqbal <haris.iqbal@cloud.ionos.com>
>
> The member queue_depth in the structure rnbd_clt_session is read from the
> rtrs client side using the function rtrs_clt_query, which in turn is read
> from the rtrs_clt structure. It should really be of type size_t.
>
> Fixes: 90426e89f54db ("block/rnbd: client: private header with client structs and functions")
> Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
> Reviewed-by: Guoqing Jiang <guoqing.jiang@ionos.com>
> Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
> ---


Looks good.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>

[PATCH for-next 2/4] block/rnbd: Fix style issues

[Gioh Kim]

From: Dima Stepanov <dmitrii.stepanov@cloud.ionos.com>

This patch fixes some style issues detected by scripts/checkpatch.pl
* Resolve spacing and tab issues
* Remove extra braces in rnbd_get_iu
* Use num_possible_cpus() instead of NR_CPUS in alloc_sess
* Fix the comments styling in rnbd_queue_rq

Signed-off-by: Dima Stepanov <dmitrii.stepanov@ionos.com>
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
---
 drivers/block/rnbd/rnbd-clt.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
index c01786afe1b1..15f831159c31 100644
--- a/drivers/block/rnbd/rnbd-clt.c
+++ b/drivers/block/rnbd/rnbd-clt.c
@@ -88,7 +88,7 @@ static int rnbd_clt_set_dev_attr(struct rnbd_clt_dev *dev,
 	dev->discard_alignment	    = le32_to_cpu(rsp->discard_alignment);
 	dev->secure_discard	    = le16_to_cpu(rsp->secure_discard);
 	dev->rotational		    = rsp->rotational;
-	dev->wc 		    = !!(rsp->cache_policy & RNBD_WRITEBACK);
+	dev->wc			    = !!(rsp->cache_policy & RNBD_WRITEBACK);
 	dev->fua		    = !!(rsp->cache_policy & RNBD_FUA);
 
 	dev->max_hw_sectors = sess->max_io_size / SECTOR_SIZE;
@@ -351,9 +351,8 @@ static struct rnbd_iu *rnbd_get_iu(struct rnbd_clt_session *sess,
 	struct rtrs_permit *permit;
 
 	iu = kzalloc(sizeof(*iu), GFP_KERNEL);
-	if (!iu) {
+	if (!iu)
 		return NULL;
-	}
 
 	permit = rnbd_get_permit(sess, con_type, wait);
 	if (unlikely(!permit)) {
@@ -805,7 +804,7 @@ static struct rnbd_clt_session *alloc_sess(const char *sessname)
 	mutex_init(&sess->lock);
 	INIT_LIST_HEAD(&sess->devs_list);
 	INIT_LIST_HEAD(&sess->list);
-	bitmap_zero(sess->cpu_queues_bm, NR_CPUS);
+	bitmap_zero(sess->cpu_queues_bm, num_possible_cpus());
 	init_waitqueue_head(&sess->rtrs_waitq);
 	refcount_set(&sess->refcount, 1);
 
@@ -1148,7 +1147,8 @@ static blk_status_t rnbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 	iu->sgt.sgl = iu->first_sgl;
 	err = sg_alloc_table_chained(&iu->sgt,
 				     /* Even-if the request has no segment,
-				      * sglist must have one entry at least */
+				      * sglist must have one entry at least.
+				      */
 				     blk_rq_nr_phys_segments(rq) ? : 1,
 				     iu->sgt.sgl,
 				     RNBD_INLINE_SG_CNT);
-- 
2.25.1

Re: [PATCH for-next 2/4] block/rnbd: Fix style issues

[Chaitanya Kulkarni]

On 4/27/21 23:14, Gioh Kim wrote:
> From: Dima Stepanov <dmitrii.stepanov@cloud.ionos.com>
>
> This patch fixes some style issues detected by scripts/checkpatch.pl
> * Resolve spacing and tab issues
> * Remove extra braces in rnbd_get_iu
> * Use num_possible_cpus() instead of NR_CPUS in alloc_sess
> * Fix the comments styling in rnbd_queue_rq
>
> Signed-off-by: Dima Stepanov <dmitrii.stepanov@ionos.com>
> Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
> Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
> Signed-off-by: Jack Wang <jinpu.wang@ionos.com>


Looks good.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>

[PATCH for-next 3/4] block/rnbd-clt: Check the return value of the function rtrs_clt_query

[Gioh Kim]

From: Md Haris Iqbal <haris.iqbal@cloud.ionos.com>

In case none of the paths are in connected state, the function
rtrs_clt_query returns an error. In such a case, error out since the
values in the rtrs_attrs structure would be garbage.

Fixes: f7a7a5c228d45 ("block/rnbd: client: main functionality")
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Reviewed-by: Guoqing Jiang <guoqing.jiang@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
---
 drivers/block/rnbd/rnbd-clt.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
index 15f831159c31..f855bf1fa8d5 100644
--- a/drivers/block/rnbd/rnbd-clt.c
+++ b/drivers/block/rnbd/rnbd-clt.c
@@ -691,7 +691,11 @@ static void remap_devs(struct rnbd_clt_session *sess)
 		return;
 	}
 
-	rtrs_clt_query(sess->rtrs, &attrs);
+	err = rtrs_clt_query(sess->rtrs, &attrs);
+	if (err) {
+		pr_err("rtrs_clt_query(\"%s\"): %d\n", sess->sessname, err);
+		return;
+	}
 	mutex_lock(&sess->lock);
 	sess->max_io_size = attrs.max_io_size;
 
@@ -1294,7 +1298,11 @@ find_and_get_or_create_sess(const char *sessname,
 		err = PTR_ERR(sess->rtrs);
 		goto wake_up_and_put;
 	}
-	rtrs_clt_query(sess->rtrs, &attrs);
+
+	err = rtrs_clt_query(sess->rtrs, &attrs);
+	if (err)
+		goto close_rtrs;
+
 	sess->max_io_size = attrs.max_io_size;
 	sess->queue_depth = attrs.queue_depth;
 	sess->nr_poll_queues = nr_poll_queues;
-- 
2.25.1

[PATCH for-next 4/4] block/rnbd: Remove all likely and unlikely

[Gioh Kim]

The IO performance test with fio after removing the likely and
unlikely macros in all if-statement shows no performance drop.
They do not help for the performance of rnbd.

The fio test did random read on 32 rnbd devices and 64 processes.
Test environment:
- AMD Opteron(tm) Processor 6386 SE
- 125G memory
- kernel version: 5.4.86
- gcc version: gcc (Debian 8.3.0-6) 8.3.0
- Infiniband controller: InfiniBand: Mellanox Technologies MT26428
[ConnectX VPI PCIe 2.0 5GT/s - IB QDR / 10GigE] (rev b0)

before
read: IOPS=549k, BW=2146MiB/s
read: IOPS=544k, BW=2125MiB/s
read: IOPS=553k, BW=2158MiB/s
read: IOPS=535k, BW=2089MiB/s
read: IOPS=543k, BW=2122MiB/s
read: IOPS=552k, BW=2154MiB/s
average: IOPS=546k, BW=2132MiB/s

after
read: IOPS=556k, BW=2172MiB/s
read: IOPS=561k, BW=2191MiB/s
read: IOPS=552k, BW=2156MiB/s
read: IOPS=551k, BW=2154MiB/s
read: IOPS=562k, BW=2194MiB/s
-----------
average: IOPS=556k, BW=2173MiB/s

The IOPS and bandwidth got better slightly after removing
likely/unlikely. (IOPS= +1.8% BW= +1.9%) But we cannot make sure
that removing the likely/unlikely help the performance because it
depends on various situations. We only make sure that removing the
likely/unlikely does not drop the performance.

Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Reviewed-by: Md Haris Iqbal <haris.iqbal@ionos.com>
---
 drivers/block/rnbd/rnbd-clt.c | 24 ++++++++++++------------
 drivers/block/rnbd/rnbd-srv.c |  2 +-
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
index f855bf1fa8d5..c604a402cd5c 100644
--- a/drivers/block/rnbd/rnbd-clt.c
+++ b/drivers/block/rnbd/rnbd-clt.c
@@ -241,7 +241,7 @@ static bool rnbd_rerun_if_needed(struct rnbd_clt_session *sess)
 	     cpu_q = rnbd_get_cpu_qlist(sess, nxt_cpu(cpu_q->cpu))) {
 		if (!spin_trylock_irqsave(&cpu_q->requeue_lock, flags))
 			continue;
-		if (unlikely(!test_bit(cpu_q->cpu, sess->cpu_queues_bm)))
+		if (!test_bit(cpu_q->cpu, sess->cpu_queues_bm))
 			goto unlock;
 		q = list_first_entry_or_null(&cpu_q->requeue_list,
 					     typeof(*q), requeue_list);
@@ -320,7 +320,7 @@ static struct rtrs_permit *rnbd_get_permit(struct rnbd_clt_session *sess,
 	struct rtrs_permit *permit;
 
 	permit = rtrs_clt_get_permit(sess->rtrs, con_type, wait);
-	if (likely(permit))
+	if (permit)
 		/* We have a subtle rare case here, when all permits can be
 		 * consumed before busy counter increased.  This is safe,
 		 * because loser will get NULL as a permit, observe 0 busy
@@ -355,7 +355,7 @@ static struct rnbd_iu *rnbd_get_iu(struct rnbd_clt_session *sess,
 		return NULL;
 
 	permit = rnbd_get_permit(sess, con_type, wait);
-	if (unlikely(!permit)) {
+	if (!permit) {
 		kfree(iu);
 		return NULL;
 	}
@@ -1050,7 +1050,7 @@ static int rnbd_client_xfer_request(struct rnbd_clt_dev *dev,
 	};
 	err = rtrs_clt_request(rq_data_dir(rq), &req_ops, rtrs, permit,
 			       &vec, 1, size, iu->sgt.sgl, sg_cnt);
-	if (unlikely(err)) {
+	if (err) {
 		rnbd_clt_err_rl(dev, "RTRS failed to transfer IO, err: %d\n",
 				 err);
 		return err;
@@ -1081,7 +1081,7 @@ static bool rnbd_clt_dev_add_to_requeue(struct rnbd_clt_dev *dev,
 	cpu_q = get_cpu_ptr(sess->cpu_queues);
 	spin_lock_irqsave(&cpu_q->requeue_lock, flags);
 
-	if (likely(!test_and_set_bit_lock(0, &q->in_list))) {
+	if (!test_and_set_bit_lock(0, &q->in_list)) {
 		if (WARN_ON(!list_empty(&q->requeue_list)))
 			goto unlock;
 
@@ -1093,7 +1093,7 @@ static bool rnbd_clt_dev_add_to_requeue(struct rnbd_clt_dev *dev,
 			 */
 			smp_mb__before_atomic();
 		}
-		if (likely(atomic_read(&sess->busy))) {
+		if (atomic_read(&sess->busy)) {
 			list_add_tail(&q->requeue_list, &cpu_q->requeue_list);
 		} else {
 			/* Very unlikely, but possible: busy counter was
@@ -1121,7 +1121,7 @@ static void rnbd_clt_dev_kick_mq_queue(struct rnbd_clt_dev *dev,
 
 	if (delay != RNBD_DELAY_IFBUSY)
 		blk_mq_delay_run_hw_queue(hctx, delay);
-	else if (unlikely(!rnbd_clt_dev_add_to_requeue(dev, q)))
+	else if (!rnbd_clt_dev_add_to_requeue(dev, q))
 		/*
 		 * If session is not busy we have to restart
 		 * the queue ourselves.
@@ -1138,12 +1138,12 @@ static blk_status_t rnbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 	int err;
 	blk_status_t ret = BLK_STS_IOERR;
 
-	if (unlikely(dev->dev_state != DEV_STATE_MAPPED))
+	if (dev->dev_state != DEV_STATE_MAPPED)
 		return BLK_STS_IOERR;
 
 	iu->permit = rnbd_get_permit(dev->sess, RTRS_IO_CON,
 				      RTRS_PERMIT_NOWAIT);
-	if (unlikely(!iu->permit)) {
+	if (!iu->permit) {
 		rnbd_clt_dev_kick_mq_queue(dev, hctx, RNBD_DELAY_IFBUSY);
 		return BLK_STS_RESOURCE;
 	}
@@ -1165,9 +1165,9 @@ static blk_status_t rnbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 
 	blk_mq_start_request(rq);
 	err = rnbd_client_xfer_request(dev, rq, iu);
-	if (likely(err == 0))
+	if (err == 0)
 		return BLK_STS_OK;
-	if (unlikely(err == -EAGAIN || err == -ENOMEM)) {
+	if (err == -EAGAIN || err == -ENOMEM) {
 		rnbd_clt_dev_kick_mq_queue(dev, hctx, 10/*ms*/);
 		ret = BLK_STS_RESOURCE;
 	}
@@ -1584,7 +1584,7 @@ struct rnbd_clt_dev *rnbd_clt_map_device(const char *sessname,
 	struct rnbd_clt_dev *dev;
 	int ret;
 
-	if (unlikely(exists_devpath(pathname, sessname)))
+	if (exists_devpath(pathname, sessname))
 		return ERR_PTR(-EEXIST);
 
 	sess = find_and_get_or_create_sess(sessname, paths, path_cnt, port_nr, nr_poll_queues);
diff --git a/drivers/block/rnbd/rnbd-srv.c b/drivers/block/rnbd/rnbd-srv.c
index 899dd9d7c10b..aafecfe97055 100644
--- a/drivers/block/rnbd/rnbd-srv.c
+++ b/drivers/block/rnbd/rnbd-srv.c
@@ -104,7 +104,7 @@ rnbd_get_sess_dev(int dev_id, struct rnbd_srv_session *srv_sess)
 
 	rcu_read_lock();
 	sess_dev = xa_load(&srv_sess->index_idr, dev_id);
-	if (likely(sess_dev))
+	if (sess_dev)
 		ret = kref_get_unless_zero(&sess_dev->kref);
 	rcu_read_unlock();
 
-- 
2.25.1

Re: [PATCH for-next 4/4] block/rnbd: Remove all likely and unlikely

[Chaitanya Kulkarni]

On 4/27/21 23:14, Gioh Kim wrote:
> The IO performance test with fio after removing the likely and
> unlikely macros in all if-statement shows no performance drop.
> They do not help for the performance of rnbd.
>
> The fio test did random read on 32 rnbd devices and 64 processes.
> Test environment:
> - AMD Opteron(tm) Processor 6386 SE
> - 125G memory
> - kernel version: 5.4.86

why 5.4 and not linux-block/for-next ?

> - gcc version: gcc (Debian 8.3.0-6) 8.3.0
> - Infiniband controller: InfiniBand: Mellanox Technologies MT26428
> [ConnectX VPI PCIe 2.0 5GT/s - IB QDR / 10GigE] (rev b0)
>
> before
> read: IOPS=549k, BW=2146MiB/s
> read: IOPS=544k, BW=2125MiB/s
> read: IOPS=553k, BW=2158MiB/s
> read: IOPS=535k, BW=2089MiB/s
> read: IOPS=543k, BW=2122MiB/s
> read: IOPS=552k, BW=2154MiB/s
> average: IOPS=546k, BW=2132MiB/s
>
> after
> read: IOPS=556k, BW=2172MiB/s
> read: IOPS=561k, BW=2191MiB/s
> read: IOPS=552k, BW=2156MiB/s
> read: IOPS=551k, BW=2154MiB/s
> read: IOPS=562k, BW=2194MiB/s
> -----------
> average: IOPS=556k, BW=2173MiB/s
>
> The IOPS and bandwidth got better slightly after removing
> likely/unlikely. (IOPS= +1.8% BW= +1.9%) But we cannot make sure
> that removing the likely/unlikely help the performance because it
> depends on various situations. We only make sure that removing the
> likely/unlikely does not drop the performance.

Did you get a chance to collect perf numbers to see which functions are
getting faster ?

Re: [PATCH for-next 4/4] block/rnbd: Remove all likely and unlikely

[Gioh Kim]

On Wed, Apr 28, 2021 at 8:33 PM Chaitanya Kulkarni
<Chaitanya.Kulkarni@wdc.com> wrote:
>
> On 4/27/21 23:14, Gioh Kim wrote:
> > The IO performance test with fio after removing the likely and
> > unlikely macros in all if-statement shows no performance drop.
> > They do not help for the performance of rnbd.
> >
> > The fio test did random read on 32 rnbd devices and 64 processes.
> > Test environment:
> > - AMD Opteron(tm) Processor 6386 SE
> > - 125G memory
> > - kernel version: 5.4.86
>
> why 5.4 and not linux-block/for-next ?

We have done porting only 5.4 for the server machine yet.

>
> > - gcc version: gcc (Debian 8.3.0-6) 8.3.0
> > - Infiniband controller: InfiniBand: Mellanox Technologies MT26428
> > [ConnectX VPI PCIe 2.0 5GT/s - IB QDR / 10GigE] (rev b0)
> >
> > before
> > read: IOPS=549k, BW=2146MiB/s
> > read: IOPS=544k, BW=2125MiB/s
> > read: IOPS=553k, BW=2158MiB/s
> > read: IOPS=535k, BW=2089MiB/s
> > read: IOPS=543k, BW=2122MiB/s
> > read: IOPS=552k, BW=2154MiB/s
> > average: IOPS=546k, BW=2132MiB/s
> >
> > after
> > read: IOPS=556k, BW=2172MiB/s
> > read: IOPS=561k, BW=2191MiB/s
> > read: IOPS=552k, BW=2156MiB/s
> > read: IOPS=551k, BW=2154MiB/s
> > read: IOPS=562k, BW=2194MiB/s
> > -----------
> > average: IOPS=556k, BW=2173MiB/s
> >
> > The IOPS and bandwidth got better slightly after removing
> > likely/unlikely. (IOPS= +1.8% BW= +1.9%) But we cannot make sure
> > that removing the likely/unlikely help the performance because it
> > depends on various situations. We only make sure that removing the
> > likely/unlikely does not drop the performance.
>
> Did you get a chance to collect perf numbers to see which functions are
> getting faster ?

I knew somebody would ask for it ;-)
No, I didn't because I have been occupied with another task.
But I will check it soon in a few weeks.

Thank you for the review.

>
>

Re: [PATCH for-next 4/4] block/rnbd: Remove all likely and unlikely

[Gioh Kim]

On Thu, Apr 29, 2021 at 9:14 AM Gioh Kim <gi-oh.kim@ionos.com> wrote:
>
> On Wed, Apr 28, 2021 at 8:33 PM Chaitanya Kulkarni
> <Chaitanya.Kulkarni@wdc.com> wrote:
> >
> > On 4/27/21 23:14, Gioh Kim wrote:
> > > The IO performance test with fio after removing the likely and
> > > unlikely macros in all if-statement shows no performance drop.
> > > They do not help for the performance of rnbd.
> > >
> > > The fio test did random read on 32 rnbd devices and 64 processes.
> > > Test environment:
> > > - AMD Opteron(tm) Processor 6386 SE
> > > - 125G memory
> > > - kernel version: 5.4.86
> >
> > why 5.4 and not linux-block/for-next ?
>
> We have done porting only 5.4 for the server machine yet.
>
> >
> > > - gcc version: gcc (Debian 8.3.0-6) 8.3.0
> > > - Infiniband controller: InfiniBand: Mellanox Technologies MT26428
> > > [ConnectX VPI PCIe 2.0 5GT/s - IB QDR / 10GigE] (rev b0)
> > >
> > > before
> > > read: IOPS=549k, BW=2146MiB/s
> > > read: IOPS=544k, BW=2125MiB/s
> > > read: IOPS=553k, BW=2158MiB/s
> > > read: IOPS=535k, BW=2089MiB/s
> > > read: IOPS=543k, BW=2122MiB/s
> > > read: IOPS=552k, BW=2154MiB/s
> > > average: IOPS=546k, BW=2132MiB/s
> > >
> > > after
> > > read: IOPS=556k, BW=2172MiB/s
> > > read: IOPS=561k, BW=2191MiB/s
> > > read: IOPS=552k, BW=2156MiB/s
> > > read: IOPS=551k, BW=2154MiB/s
> > > read: IOPS=562k, BW=2194MiB/s
> > > -----------
> > > average: IOPS=556k, BW=2173MiB/s
> > >
> > > The IOPS and bandwidth got better slightly after removing
> > > likely/unlikely. (IOPS= +1.8% BW= +1.9%) But we cannot make sure
> > > that removing the likely/unlikely help the performance because it
> > > depends on various situations. We only make sure that removing the
> > > likely/unlikely does not drop the performance.
> >
> > Did you get a chance to collect perf numbers to see which functions are
> > getting faster ?

Hi Chaitanya,

I ran the perf tool to find out which functions are getting faster.
But I was not able to find it.
Could you please suggest a tool or anything to check it out?

For your information, below is what I got with 'perf record fio
<options:8-device, 64-job, 60-second>'
The result before/after removing likely/unlikely looks the same.

     4.15%  fio      [kernel.kallsyms]    [k] _raw_spin_lock_irqsave
     3.19%  fio      [kernel.kallsyms]    [k] x86_pmu_disable_all
     2.98%  fio      [rnbd_client]        [k] rnbd_put_permit
     2.77%  fio      [kernel.kallsyms]    [k] find_first_zero_bit
     2.49%  fio      [kernel.kallsyms]    [k] __x86_indirect_thunk_rax
     2.21%  fio      [kernel.kallsyms]    [k] psi_task_change
     2.00%  fio      [kernel.kallsyms]    [k] gup_pgd_range
     1.83%  fio      fio                  [.] 0x0000000000029048
     1.78%  fio      [rnbd_client]        [k] rnbd_get_permit
     1.78%  fio      fio                  [.] axmap_isset
     1.63%  fio      [kernel.kallsyms]    [k] _raw_spin_lock
     1.58%  fio      fio                  [.] fio_gettime
     1.53%  fio      [rtrs_client]        [k] __rtrs_get_permit
     1.51%  fio      [rnbd_client]        [k] rnbd_queue_rq
     1.51%  fio      [rtrs_client]        [k] rtrs_clt_put_permit
     1.47%  fio      [kernel.kallsyms]    [k] try_to_wake_up
     1.31%  fio      [kernel.kallsyms]    [k] kmem_cache_alloc
     1.22%  fio      libc-2.28.so         [.] 0x00000000000a2547
     1.17%  fio      [mlx4_ib]            [k] _mlx4_ib_post_send
     1.14%  fio      [kernel.kallsyms]    [k] blkdev_direct_IO
     1.14%  fio      [kernel.kallsyms]    [k] read_tsc
     1.02%  fio      [rtrs_client]        [k] rtrs_clt_read_req
     0.92%  fio      [rtrs_client]        [k] get_next_path_min_inflight
     0.92%  fio      [kernel.kallsyms]    [k] sched_clock
     0.91%  fio      [kernel.kallsyms]    [k] blk_mq_get_request
     0.87%  fio      [kernel.kallsyms]    [k] x86_pmu_enable_all
     0.87%  fio      [kernel.kallsyms]    [k] __sched_text_start
     0.84%  fio      [kernel.kallsyms]    [k] insert_work
     0.82%  fio      [kernel.kallsyms]    [k] copy_user_generic_string
     0.80%  fio      [kernel.kallsyms]    [k] blk_attempt_plug_merge
     0.73%  fio      [rtrs_client]        [k] rtrs_clt_update_all_stats


>
> I knew somebody would ask for it ;-)
> No, I didn't because I have been occupied with another task.
> But I will check it soon in a few weeks.
>
> Thank you for the review.
>
> >
> >

Re: [PATCH for-next 4/4] block/rnbd: Remove all likely and unlikely

[Gioh Kim]

On Tue, May 4, 2021 at 3:04 PM Gioh Kim <gi-oh.kim@ionos.com> wrote:
>
> On Thu, Apr 29, 2021 at 9:14 AM Gioh Kim <gi-oh.kim@ionos.com> wrote:
> >
> > On Wed, Apr 28, 2021 at 8:33 PM Chaitanya Kulkarni
> > <Chaitanya.Kulkarni@wdc.com> wrote:
> > >
> > > On 4/27/21 23:14, Gioh Kim wrote:
> > > > The IO performance test with fio after removing the likely and
> > > > unlikely macros in all if-statement shows no performance drop.
> > > > They do not help for the performance of rnbd.
> > > >
> > > > The fio test did random read on 32 rnbd devices and 64 processes.
> > > > Test environment:
> > > > - AMD Opteron(tm) Processor 6386 SE
> > > > - 125G memory
> > > > - kernel version: 5.4.86
> > >
> > > why 5.4 and not linux-block/for-next ?
> >
> > We have done porting only 5.4 for the server machine yet.
> >
> > >
> > > > - gcc version: gcc (Debian 8.3.0-6) 8.3.0
> > > > - Infiniband controller: InfiniBand: Mellanox Technologies MT26428
> > > > [ConnectX VPI PCIe 2.0 5GT/s - IB QDR / 10GigE] (rev b0)
> > > >
> > > > before
> > > > read: IOPS=549k, BW=2146MiB/s
> > > > read: IOPS=544k, BW=2125MiB/s
> > > > read: IOPS=553k, BW=2158MiB/s
> > > > read: IOPS=535k, BW=2089MiB/s
> > > > read: IOPS=543k, BW=2122MiB/s
> > > > read: IOPS=552k, BW=2154MiB/s
> > > > average: IOPS=546k, BW=2132MiB/s
> > > >
> > > > after
> > > > read: IOPS=556k, BW=2172MiB/s
> > > > read: IOPS=561k, BW=2191MiB/s
> > > > read: IOPS=552k, BW=2156MiB/s
> > > > read: IOPS=551k, BW=2154MiB/s
> > > > read: IOPS=562k, BW=2194MiB/s
> > > > -----------
> > > > average: IOPS=556k, BW=2173MiB/s
> > > >
> > > > The IOPS and bandwidth got better slightly after removing
> > > > likely/unlikely. (IOPS= +1.8% BW= +1.9%) But we cannot make sure
> > > > that removing the likely/unlikely help the performance because it
> > > > depends on various situations. We only make sure that removing the
> > > > likely/unlikely does not drop the performance.
> > >
> > > Did you get a chance to collect perf numbers to see which functions are
> > > getting faster ?
>
> Hi Chaitanya,
>
> I ran the perf tool to find out which functions are getting faster.
> But I was not able to find it.
> Could you please suggest a tool or anything to check it out?
>
> For your information, below is what I got with 'perf record fio
> <options:8-device, 64-job, 60-second>'
> The result before/after removing likely/unlikely looks the same.
>
>      4.15%  fio      [kernel.kallsyms]    [k] _raw_spin_lock_irqsave
>      3.19%  fio      [kernel.kallsyms]    [k] x86_pmu_disable_all
>      2.98%  fio      [rnbd_client]        [k] rnbd_put_permit
>      2.77%  fio      [kernel.kallsyms]    [k] find_first_zero_bit
>      2.49%  fio      [kernel.kallsyms]    [k] __x86_indirect_thunk_rax
>      2.21%  fio      [kernel.kallsyms]    [k] psi_task_change
>      2.00%  fio      [kernel.kallsyms]    [k] gup_pgd_range
>      1.83%  fio      fio                  [.] 0x0000000000029048
>      1.78%  fio      [rnbd_client]        [k] rnbd_get_permit
>      1.78%  fio      fio                  [.] axmap_isset
>      1.63%  fio      [kernel.kallsyms]    [k] _raw_spin_lock
>      1.58%  fio      fio                  [.] fio_gettime
>      1.53%  fio      [rtrs_client]        [k] __rtrs_get_permit
>      1.51%  fio      [rnbd_client]        [k] rnbd_queue_rq
>      1.51%  fio      [rtrs_client]        [k] rtrs_clt_put_permit
>      1.47%  fio      [kernel.kallsyms]    [k] try_to_wake_up
>      1.31%  fio      [kernel.kallsyms]    [k] kmem_cache_alloc
>      1.22%  fio      libc-2.28.so         [.] 0x00000000000a2547
>      1.17%  fio      [mlx4_ib]            [k] _mlx4_ib_post_send
>      1.14%  fio      [kernel.kallsyms]    [k] blkdev_direct_IO
>      1.14%  fio      [kernel.kallsyms]    [k] read_tsc
>      1.02%  fio      [rtrs_client]        [k] rtrs_clt_read_req
>      0.92%  fio      [rtrs_client]        [k] get_next_path_min_inflight
>      0.92%  fio      [kernel.kallsyms]    [k] sched_clock
>      0.91%  fio      [kernel.kallsyms]    [k] blk_mq_get_request
>      0.87%  fio      [kernel.kallsyms]    [k] x86_pmu_enable_all
>      0.87%  fio      [kernel.kallsyms]    [k] __sched_text_start
>      0.84%  fio      [kernel.kallsyms]    [k] insert_work
>      0.82%  fio      [kernel.kallsyms]    [k] copy_user_generic_string
>      0.80%  fio      [kernel.kallsyms]    [k] blk_attempt_plug_merge
>      0.73%  fio      [rtrs_client]        [k] rtrs_clt_update_all_stats
>

Hi Chaitanya,

I think likely/unlikely macros are related to cache and branch prediction.
So I checked cache and branch misses with perf tool.

The result are same before/after removing likely/unlikely
- cache misses: after 5,452%, before 5,443%
- branch misses: after 2.08%, before 2.09%

I would appreciate it if you would suggest something else for me to check.

Below is the raw data that I got from the perf tool.

after removing likely:
 Performance counter stats for 'fio --direct=1 --rw=randread
--time_based=1 --group_reporting --ioengine=libaio --iodepth=128
--name=fiotest --fadvise_hint=0 --iodepth_batch_submit=128
--iodepth_batch_complete=128 --invalidate=0 --runtime=180 --numjobs=64
--filename=/dev/rnbd0 --filename=/dev/rnbd1 --filename=/dev/rnbd2
--filename=/dev/rnbd3 --filename=/dev/rnbd4 --filename=/dev/rnbd5
--filename=/dev/rnbd6 --filename=/dev/rnbd7 --filename=/dev/rnbd8
--filename=/dev/rnbd9 --filename=/dev/rnbd10 --filename=/dev/rnbd11
--filename=/dev/rnbd12 --filename=/dev/rnbd13 --filename=/dev/rnbd14
--filename=/dev/rnbd15 --filename=/dev/rnbd16 --filename=/dev/rnbd17
--filename=/dev/rnbd18 --filename=/dev/rnbd19 --filename=/dev/rnbd20
--filename=/dev/rnbd21 --filename=/dev/rnbd22 --filename=/dev/rnbd23
--filename=/dev/rnbd24 --filename=/dev/rnbd25 --filename=/dev/rnbd26
--filename=/dev/rnbd27 --filename=/dev/rnbd28 --filename=/dev/rnbd29
--filename=/dev/rnbd30 --filename=/dev/rnbd31':

      1.834.487,82 msec task-clock                #    9,986 CPUs
utilized
 3.128.339.845.336      cycles                    #    1,705 GHz
               (66,53%)
 1.110.316.024.909      instructions              #    0,35  insn per
cycle           (83,27%)
    76.626.760.535      cache-references          #   41,770 M/sec
               (83,26%)
     4.177.366.104      cache-misses              #    5,452 % of all
cache refs      (50,21%)
   224.055.600.184      branches                  #  122,135 M/sec
               (66,85%)
     4.669.404.288      branch-misses             #    2,08% of all
branches          (83,38%)

     183,707988693 seconds time elapsed
     185,630125000 seconds user
    1590,286666000 seconds sys

before removing:
 Performance counter stats for 'fio --direct=1 --rw=randread
--time_based=1 --group_reporting --ioengine=libaio --iodepth=128
--name=fiotest --fadvise_hint=0 --iodepth_batch_submit=128
--iodepth_batch_complete=128 --invalidate=0 --runtime=180 --numjobs=64
--filename=/dev/rnbd0 --filename=/dev/rnbd1 --filename=/dev/rnbd2
--filename=/dev/rnbd3 --filename=/dev/rnbd4 --filename=/dev/rnbd5
--filename=/dev/rnbd6 --filename=/dev/rnbd7 --filename=/dev/rnbd8
--filename=/dev/rnbd9 --filename=/dev/rnbd10 --filename=/dev/rnbd11
--filename=/dev/rnbd12 --filename=/dev/rnbd13 --filename=/dev/rnbd14
--filename=/dev/rnbd15 --filename=/dev/rnbd16 --filename=/dev/rnbd17
--filename=/dev/rnbd18 --filename=/dev/rnbd19 --filename=/dev/rnbd20
--filename=/dev/rnbd21 --filename=/dev/rnbd22 --filename=/dev/rnbd23
--filename=/dev/rnbd24 --filename=/dev/rnbd25 --filename=/dev/rnbd26
--filename=/dev/rnbd27 --filename=/dev/rnbd28 --filename=/dev/rnbd29
--filename=/dev/rnbd30 --filename=/dev/rnbd31':

      1.841.874,78 msec task-clock                #   10,039 CPUs
utilized
 3.157.131.978.349      cycles                    #    1,714 GHz
               (66,48%)
 1.115.369.402.018      instructions              #    0,35  insn per
cycle           (83,27%)
    77.060.091.803      cache-references          #   41,838 M/sec
               (83,39%)
     4.194.110.754      cache-misses              #    5,443 % of all
cache refs      (50,13%)
   225.304.135.864      branches                  #  122,323 M/sec
               (66,83%)
     4.716.162.562      branch-misses             #    2,09% of all
branches          (83,42%)

     183,476417386 seconds time elapsed
     185,356439000 seconds user
    1596,787284000 seconds sys



>
> >
> > I knew somebody would ask for it ;-)
> > No, I didn't because I have been occupied with another task.
> > But I will check it soon in a few weeks.
> >
> > Thank you for the review.
> >
> > >
> > >

Re: [PATCH for-next 0/4] Misc update for RNBD

[Jens Axboe]

On 4/28/21 12:13 AM, Gioh Kim wrote:
> Some misc updates for RNBD:
> * Remove unnecessary likely/unlikely macro from if-else statement
> * Fix coding style issues reported by checkpatch.pl
> * Add error check

Applied for post initial merge, thanks.

-- 
Jens Axboe