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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: Fri, 16 Apr 2021 08:46:10 +0800	[thread overview]
Message-ID: <YHjeUrCTbrSft18t@T590> (raw)
In-Reply-To: <f66f9204-83ff-48d4-dbf4-4a5e1dc100b7@huawei.com>

On Thu, Apr 15, 2021 at 04:41:06PM +0100, John Garry wrote:
> On 15/04/2021 13:18, Ming Lei wrote:
> > 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.
> > 
> 
> Hi Ming,
> 
> I can't seem to recreate your same issue. Are you mainline defconfig, or a
> special disto config?

The config is rhel8 config.

As I mentioned, with deadline, IOPS drop is observed on one hardware(ibm-x3850x6)
which is exactly the machine Yanhui reported the cpu utilization issue.

On another machine(HP DL380G10), still 32cores, dual numa nodes, IOPS drop can't be
observed, but cpu utilization difference is still obserable.

I use scsi_debug just because it is hard to run the virt workloads on
that machine. And the reported issue is on megaraid_sas, which is a scsi
device, so null_blk isn't good to simulate here because it can't cover
scsi stack.


Thanks,
Ming


  reply	other threads:[~2021-04-16  0:46 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
2021-04-15 15:41               ` John Garry
2021-04-16  0:46                 ` Ming Lei [this message]
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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