linux-kernel - Re: 6.10/regression/bisected - after f1d97e769152 I spotted increased execution time of the kswapd0 process and symptoms as if there is not enough memory

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Message-ID: <CAL3q7H7MP7HQbyMpGgRrG+rejQX+5Hc7ipPNPN_tjbaUzNBNGQ@mail.gmail.com>
Date: Fri, 5 Jul 2024 12:06:04 +0100
From: Filipe Manana <fdmanana@...nel.org>
To: Andrea Gelmini <andrea.gelmini@...il.com>
Cc: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>, 
	Linux List Kernel Mailing <linux-kernel@...r.kernel.org>, 
	Linux regressions mailing list <regressions@...ts.linux.dev>, Btrfs BTRFS <linux-btrfs@...r.kernel.org>, 
	dsterba@...e.com, josef@...icpanda.com
Subject: Re: 6.10/regression/bisected - after f1d97e769152 I spotted increased
 execution time of the kswapd0 process and symptoms as if there is not enough memory

On Fri, Jul 5, 2024 at 7:30 AM Andrea Gelmini <andrea.gelmini@...il.com> wrote:
>
> Il giorno gio 4 lug 2024 alle ore 19:25 Filipe Manana
> <fdmanana@...nel.org> ha scritto:
> > 1) First let's check that the problem is really a consequence of the shrinker.
> >     Try this patch:
> >
> >     https://gist.githubusercontent.com/fdmanana/b44abaade0000d28ba0e1e1ae3ac4fee/raw/5c9bf0beb5aa156b893be2837c9244d035962c74/gistfile1.txt
> >
> >     This disables the shrinker. This is just to confirm if I'm looking
> > in the right direction, if your problem is the same as Mikhail's and
> > double check his bisection.
>
> Ok, so, I confirm. With this change, just a little bit of PSI memory
> sometime (<3%), but no skyrocket. Also, tar at full speed.

Ok, so the bisection is reliable and it means you are experiencing the
same problem that Mikhail reported.

>
> Now, I'm going to prepare the btrfs image to send you.

That might not be necessary, not sure how it would help, the 2nd patch
to try would confirm if it's any fragmentation causing too many slow
reads after extent map eviction.
So save yourself some time for now because making the image is likely slow.

>
> The other steps later.

Thanks!