Re: [PATCH 0/5] writeback: Fix bandwidth estimates

From: Michael Stapelberg <stapelberg+linux@google.com>
To: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org,  linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH 0/5] writeback: Fix bandwidth estimates
Date: Tue, 13 Jul 2021 10:15:33 +0200	[thread overview]
Message-ID: <CAH9Oa-b9DT78Thja1QHTUk3jQTD5A0kbzRGM6b2SBjPdd5Mehg@mail.gmail.com> (raw)
In-Reply-To: <20210712162733.GB9804@quack2.suse.cz>

[-- Attachment #1: Type: text/plain, Size: 1290 bytes --]

Yes! Thank you.

On Mon, 12 Jul 2021 at 18:27, Jan Kara <jack@suse.cz> wrote:

> On Fri 09-07-21 15:19:17, Michael Stapelberg wrote:
> > Thanks for sending this patch series!
> >
> > I have used the mmap.c reproducer as before, with the following
> parameters:
> > * mkdir /tmp/mnt
> > * fusermount -u /tmp/mnt; /root/fuse-2.9.9/example/fusexmp_fh -f /tmp/mnt
> > * dd if=/dev/urandom of=/tmp/was bs=1M count=99
> > * while :; do grep ^Bdi /sys/kernel/debug/bdi/0:44/stats; sleep 0.1; done
> > * while :; do time WORKAROUND=1 ~/mmap /tmp/was
> > /tmp/mnt/tmp/stapelberg.1; sleep 5; done
> >
> > Previously, after a few iterations, the BdiWriteBandwidth measure
> > would gradually approach 0.
> >
> > With your patch series applied, the BdiWriteBandwidth is updated much
> > more quickly, and converges to ≈16000 kBps.
> > When I start copying more quickly, the bandwidth measure rises quickly.
> >
> > As far as I understand, this should fix the problem (provided 16000
> > kBps is an okay value).
> > Certainly, I don’t see the downward spiral either with your patches :)
>
> Thanks for testing! Can I add your Tested-by tag?
>
>                                                                 Honza
> --
> Jan Kara <jack@suse.com>
> SUSE Labs, CR
>

[-- Attachment #2: Type: text/html, Size: 1764 bytes --]