linux-kernel - Re: [PATCH 14/14] skip readahead if the cgroup is congested

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Message-ID: <20180702211357.GN533219@devbig577.frc2.facebook.com>
Date:   Mon, 2 Jul 2018 14:13:57 -0700
From:   Tejun Heo <tj@...nel.org>
To:     Josef Bacik <josef@...icpanda.com>
Cc:     axboe@...nel.dk, kernel-team@...com, linux-block@...r.kernel.org,
        akpm@...ux-foundation.org, hannes@...xchg.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Josef Bacik <jbacik@...com>
Subject: Re: [PATCH 14/14] skip readahead if the cgroup is congested

On Fri, Jun 29, 2018 at 03:25:42PM -0400, Josef Bacik wrote:
> From: Josef Bacik <jbacik@...com>
> 
> We noticed in testing we'd get pretty bad latency stalls under heavy
> pressure because read ahead would try to do its thing while the cgroup
> was under severe pressure.  If we're under this much pressure we want to
> do as little IO as possible so we can still make progress on real work
> if we're a throttled cgroup, so just skip readahead if our group is
> under pressure.
> 
> Signed-off-by: Josef Bacik <jbacik@...com>

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun