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Subject: Re: [PATCH RESEND] block: annotate refault stalls from IO submission
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     Dave Chinner <david@fromorbit.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20190808190300.GA9067@cmpxchg.org>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <4ad47b61-e917-16cc-95a0-18e070b6b4e0@kernel.dk>
Date:   Wed, 14 Aug 2019 08:50:32 -0600
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On 8/8/19 1:03 PM, Johannes Weiner wrote:
> psi tracks the time tasks wait for refaulting pages to become
> uptodate, but it does not track the time spent submitting the IO. The
> submission part can be significant if backing storage is contended or
> when cgroup throttling (io.latency) is in effect - a lot of time is
> spent in submit_bio(). In that case, we underreport memory pressure.
> 
> Annotate submit_bio() to account submission time as memory stall when
> the bio is reading userspace workingset pages.

Applied for 5.4.

-- 
Jens Axboe