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From: "Michal Koutný" <mkoutny@suse.com>
To: Yosry Ahmed <yosry@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>, Zenghui Yu <zenghui.yu@linux.dev>,
	 linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kselftest@vger.kernel.org,  linux-kernel@vger.kernel.org,
	hannes@cmpxchg.org, chengming.zhou@linux.dev, tj@kernel.org,
	 Shuah Khan <shuah@kernel.org>,
	mhocko@kernel.org, Roman Gushchin <roman.gushchin@linux.dev>,
	 Shakeel Butt <shakeel.butt@linux.dev>,
	Muchun Song <muchun.song@linux.dev>,
	 Andrew Morton <akpm@linux-foundation.org>
Subject: Re: cgroup/test_zswap failed with "zswpout does not increase after test program"
Date: Wed, 8 Jul 2026 21:00:54 +0200	[thread overview]
Message-ID: <ak6c2TaOlcGxZ2Ih@localhost.localdomain> (raw)
In-Reply-To: <CAO9r8zM8qk9g6+B6GiCV3oytjViMTEhbr0KjrccU+bF4+PMfTA@mail.gmail.com>

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On Tue, Jul 07, 2026 at 02:49:56PM -0700, Yosry Ahmed <yosry@kernel.org> wrote:
> I would honestly rather use more memory. I think there might be cases
> where the flusher is delayed. The flush being slightly delayed is not
> technically a bug that we want to see a failure for, but if a large
> stats change is not visible that's a user-noticeable behavior that we
> want a failure for.
> 
> WDYT?

There's already the (recent) page size-based scaling, so the idea with
nr_cpus scaling could make the selftest useful on wider range of setups
(even page size can be considered as a slight implementation detail
leak, thus the justification of nr_cpus dependency).

Also, I still think that internally the threshold should be changed to
the "harmonic" formula [1] but the selftest can go with the linear
dependency for more pronounced effects.

Thanks,
Michal

[1] https://lore.kernel.org/lkml/n6mhkjsxsami3qmczkdh57eep4lmcgbtyl7ox3ajzveke44yf6@m4bjevvsr47k/

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  reply	other threads:[~2026-07-08 19:00 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-07  9:38 cgroup/test_zswap failed with "zswpout does not increase after test program" Zenghui Yu
2026-07-07 12:01 ` Michal Koutný
2026-07-07 12:14   ` Zenghui Yu
2026-07-07 18:25 ` Yosry Ahmed
2026-07-07 21:35   ` Nhat Pham
2026-07-07 21:36     ` Yosry Ahmed
2026-07-07 21:46       ` Nhat Pham
2026-07-07 21:49         ` Yosry Ahmed
2026-07-08 19:00           ` Michal Koutný [this message]
2026-07-08 19:08             ` Yosry Ahmed
2026-07-10 17:30               ` Nhat Pham
2026-07-10 18:25                 ` Yosry Ahmed

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