From: Ming Lei <ming.lei@redhat.com>
To: John Garry <john.garry@huawei.com>
Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
Kashyap Desai <kashyap.desai@broadcom.com>,
"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: Wed, 14 Apr 2021 18:38:49 +0800 [thread overview]
Message-ID: <YHbGOWnVbMjFV7TI@T590> (raw)
In-Reply-To: <9a6145a5-e6ac-3d33-b52a-0823bfc3b864@huawei.com>
On Wed, Apr 14, 2021 at 11:10:39AM +0100, John Garry wrote:
> Hi Ming,
>
> >
> > It is reported inside RH that CPU utilization is increased ~20% when
> > running simple FIO test inside VM which disk is built on image stored
> > on XFS/megaraid_sas.
> >
> > When I try to investigate by reproducing the issue via scsi_debug, I found
> > IO hang when running randread IO(8k, direct IO, libaio) on scsi_debug disk
> > created by the following command:
> >
> > modprobe scsi_debug host_max_queue=128 submit_queues=$NR_CPUS virtual_gb=256
> >
>
> So I can recreate this hang for using mq-deadline IO sched for scsi debug,
> in that fio does not exit. I'm using v5.12-rc7.
>
> Do you have any idea of what changed to cause this, as we would have tested
> this before? Or maybe only none IO sched on scsi_debug. And normally 4k
> block size and only rw=read (for me, anyway).
Just run a quick test with none on scsi_debug, looks the issue can't be
reproduced, but very worse performance is observed with none(20% IOPS drops,
and 50% CPU utilization increased).
>
> Note that host_max_queue=128 will cap submit queue depth at 128, while would
> be 192 by default.
I take 128 because the reported megaraid_sas's host queue depth is 128.
Thanks,
Ming
next prev parent reply other threads:[~2021-04-14 10:39 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YHbGOWnVbMjFV7TI@T590 \
--to=ming.lei@redhat.com \
--cc=axboe@kernel.dk \
--cc=dgilbert@interlog.com \
--cc=john.garry@huawei.com \
--cc=kashyap.desai@broadcom.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=martin.petersen@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).