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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>,
	Hannes Reinecke <hare@suse.com>
Subject: Re: [bug report] shared tags causes IO hang and performance drop
Date: Tue, 27 Apr 2021 17:11:49 +0800	[thread overview]
Message-ID: <YIfVVRheF9ZWjzbh@T590> (raw)
In-Reply-To: <ab83eec4-20f1-ad74-7f43-52a4a87a8aa9@huawei.com>

On Tue, Apr 27, 2021 at 08:52:53AM +0100, John Garry wrote:
> On 27/04/2021 00:59, Ming Lei wrote:
> > > Anyway, I'll look at adding code for a per-request queue sched tags to see
> > > if it helps. But I would plan to continue to use a per hctx sched request
> > > pool.
> > Why not switch to per hctx sched request pool?
> 
> I don't understand. The current code uses a per-hctx sched request pool, and
> I said that I don't plan to change that.

I forget why you didn't do that, because for hostwide tags, request
is always 1:1 for either sched tags(real io sched) or driver tags(none).

Maybe you want to keep request local to hctx, but never see related
performance data for supporting the point, sbitmap queue allocator has
been intelligent enough to allocate tag freed from native cpu.

Then you just waste lots of memory, I remember that scsi request payload
is a bit big.


Thanks,
Ming


  reply	other threads:[~2021-04-27  9:12 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
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 [this message]
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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