linux-kernel - Re: single aio thread is migrated crazily by scheduler

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Date:   Tue, 19 Nov 2019 16:54:52 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Dave Chinner <david@...morbit.com>
Cc:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jeff Moyer <jmoyer@...hat.com>,
        Dave Chinner <dchinner@...hat.com>,
        Eric Sandeen <sandeen@...hat.com>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tejun Heo <tj@...nel.org>
Subject: Re: single aio thread is migrated crazily by scheduler

On Tue, Nov 19, 2019 at 08:18:04AM +1100, Dave Chinner wrote:
> On Mon, Nov 18, 2019 at 09:56:33PM +0530, Srikar Dronamraju wrote:
> > * Dave Chinner <david@...morbit.com> [2019-11-16 10:40:05]:
> > 
> > > On Fri, Nov 15, 2019 at 03:08:43PM +0800, Ming Lei wrote:
> > > > On Fri, Nov 15, 2019 at 03:56:34PM +1100, Dave Chinner wrote:
> > > > > On Fri, Nov 15, 2019 at 09:08:24AM +0800, Ming Lei wrote:
> > > > I can reproduce the issue with 4k block size on another RH system, and
> > > > the login info of that system has been shared to you in RH BZ.
> > > > 
> > > > 1)
> > > 
> > > Almost all the fio task migrations are coming from migration/X
> > > kernel threads. i.e it's the scheduler active balancing that is
> > > causing the fio thread to bounce around.
> > > 
> > 
> > Can we try with the below patch.
> 
> That makes things much, much worse.

Yeah, it is same with my test result, basically the fio io thread
migration counts is increased from 5k to 8k.

Thanks,
Ming