From: Ming Lei <ming.lei@redhat.com>
To: John Garry <john.garry@huawei.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>,
linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Jens Axboe <axboe@kernel.dk>,
Douglas Gilbert <dgilbert@interlog.com>
Subject: Re: [bug report] shared tags causes IO hang and performance drop
Date: Thu, 15 Apr 2021 20:18:56 +0800 [thread overview]
Message-ID: <YHgvMAHqIq9f6pQn@T590> (raw)
In-Reply-To: <3e76ffc7-1d71-83b6-ef5b-3986e947e372@huawei.com>
On Thu, Apr 15, 2021 at 11:41:52AM +0100, John Garry wrote:
> Hi Ming,
>
> I'll have a look.
>
> BTW, are you intentionally using scsi_debug over null_blk? null_blk supports
> shared sbitmap as well, and performance figures there are generally higher
> than scsi_debug for similar fio settings.
I use both, but scsi_debug can cover scsi stack test.
Thanks,
Ming
>
> Thanks,
> john
>
> EOM
>
>
> > > IOPs
> > > mq-deadline usr=21.72%, sys=44.18%, 423K
> > > none usr=23.15%, sys=74.01% 450K
> > Today I re-run the scsi_debug test on two server hardwares(32cores, dual
> > numa nodes), and the CPU utilization issue can be reproduced, follow
> > the test result:
> >
> > 1) randread test on ibm-x3850x6[*] with deadline
> >
> > |IOPS | FIO CPU util
> > ------------------------------------------------
> > hosttags | 94k | usr=1.13%, sys=14.75%
> > ------------------------------------------------
> > non hosttags | 124k | usr=1.12%, sys=10.65%,
> >
> >
> > 2) randread test on ibm-x3850x6[*] with none
> > |IOPS | FIO CPU util
> > ------------------------------------------------
> > hosttags | 120k | usr=0.89%, sys=6.55%
> > ------------------------------------------------
> > non hosttags | 121k | usr=1.07%, sys=7.35%
> > ------------------------------------------------
> >
> > *:
> > - that is the machine Yanhui reported VM cpu utilization increased by 20%
> > - kernel: latest linus tree(v5.12-rc7, commit: 7f75285ca57)
> > - also run same test on another 32cores machine, IOPS drop isn't
> > observed, but CPU utilization is increased obviously
> >
> > 3) test script
> > #/bin/bash
> >
> > run_fio() {
> > RTIME=$1
> > JOBS=$2
> > DEVS=$3
> > BS=$4
> >
> > QD=64
> > BATCH=16
> >
> > fio --bs=$BS --ioengine=libaio \
> > --iodepth=$QD \
> > --iodepth_batch_submit=$BATCH \
> > --iodepth_batch_complete_min=$BATCH \
> > --filename=$DEVS \
> > --direct=1 --runtime=$RTIME --numjobs=$JOBS --rw=randread \
> > --name=test --group_reporting
> > }
> >
> > SCHED=$1
> >
> > NRQS=`getconf _NPROCESSORS_ONLN`
> >
> > rmmod scsi_debug
> > modprobe scsi_debug host_max_queue=128 submit_queues=$NRQS virtual_gb=256
> > sleep 2
> > DEV=`lsscsi | grep scsi_debug | awk '{print $6}'`
> > echo $SCHED >/sys/block/`basename $DEV`/queue/scheduler
> > echo 128 >/sys/block/`basename $DEV`/device/queue_depth
> > run_fio 20 16 $DEV 8K
> >
> >
> > rmmod scsi_debug
> > modprobe scsi_debug max_queue=128 submit_queues=1 virtual_gb=256
> > sleep 2
> > DEV=`lsscsi | grep scsi_debug | awk '{print $6}'`
> > echo $SCHED >/sys/block/`basename $DEV`/queue/scheduler
> > echo 128 >/sys/block/`basename $DEV`/device/queue_depth
> > run_fio 20 16 $DEV 8k
>
>
--
Ming
next prev parent reply other threads:[~2021-04-15 12:19 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-14 7:50 [bug report] shared tags causes IO hang and performance drop Ming Lei
2021-04-14 10:10 ` John Garry
2021-04-14 10:38 ` Ming Lei
2021-04-14 10:42 ` Kashyap Desai
2021-04-14 11:12 ` Ming Lei
2021-04-14 12:06 ` John Garry
2021-04-15 3:46 ` Ming Lei
2021-04-15 10:41 ` John Garry
2021-04-15 12:18 ` Ming Lei [this message]
2021-04-15 15:41 ` John Garry
2021-04-16 0:46 ` Ming Lei
2021-04-16 8:29 ` John Garry
2021-04-16 8:39 ` Ming Lei
2021-04-16 14:59 ` John Garry
2021-04-20 3:06 ` Douglas Gilbert
2021-04-20 3:22 ` Bart Van Assche
2021-04-20 4:54 ` Douglas Gilbert
2021-04-20 6:52 ` Ming Lei
2021-04-20 20:22 ` Douglas Gilbert
2021-04-21 1:40 ` Ming Lei
2021-04-23 8:43 ` John Garry
2021-04-26 10:53 ` John Garry
2021-04-26 14:48 ` Ming Lei
2021-04-26 15:52 ` John Garry
2021-04-26 16:03 ` Ming Lei
2021-04-26 17:02 ` John Garry
2021-04-26 23:59 ` Ming Lei
2021-04-27 7:52 ` John Garry
2021-04-27 9:11 ` Ming Lei
2021-04-27 9:37 ` John Garry
2021-04-27 9:52 ` Ming Lei
2021-04-27 10:15 ` John Garry
2021-07-07 17:06 ` John Garry
2021-04-14 13:59 ` Kashyap Desai
2021-04-14 17:03 ` Douglas Gilbert
2021-04-14 18:19 ` John Garry
2021-04-14 19:39 ` Douglas Gilbert
2021-04-15 0:58 ` Ming Lei
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