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From: Karl Mehltretter <kmehltretter@gmail.com>
To: KunWu Chan <kunwu.chan@gmail.com>
Cc: SJ Park <sj@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	 Lian Wang <lianux.mm@gmail.com>,
	damon@lists.linux.dev, linux-mm@kvack.org,
	 linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm/damon/tests/core-kunit: test PSI goal rounds under the temporal tuner
Date: Tue, 15 Sep 2026 23:31:02 +0200	[thread overview]
Message-ID: <aqm4xSben7Aq1iNO@gmail.com> (raw)
In-Reply-To: <CAN_Opa9rS45S_MHbmf63KC0LY9AGAdAC5r=vv_qcYMVAenWosQ@mail.gmail.com>

On Tue, Sep 15, 2026 at 03:04:06PM +0100, KunWu Chan wrote:
> Could we also check goal->last_psi_total here?
> 
> The first tuning round should consume the U64_MAX sentinel
> and establish the measured state.
> 
> Testing this explicitly would lock in that state transition.
> 

Thanks for the review, good idea! The test only inferred the state
from the effective quota, a direct check of last_psi_total is clearer
and stricter.

It also fits the v2 fix. I plan to keep last_psi_total across a
commit of an existing PSI goal instead of touching the tuners, so
that value is what the test should assert.

For the v2 test I plan to check last_psi_total at each transition:
not U64_MAX after the first round, still the kept sample after a
commit of the same metric, U64_MAX again after a commit that changes
the metric and back. The quota checks stay to cover the tuners.

Karl

  reply	other threads:[~2026-09-15 21:31 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-15  6:09 [PATCH 0/2] mm/damon: fix zero quota for PSI goals " Karl Mehltretter
2026-09-15  6:09 ` [PATCH 1/2] mm/damon/core: score an unmeasured PSI goal as not achieved for " Karl Mehltretter
2026-09-15 14:50   ` SJ Park
2026-09-15 21:19     ` Karl Mehltretter
2026-09-16  0:13       ` SJ Park
2026-09-15  6:09 ` [PATCH 2/2] mm/damon/tests/core-kunit: test PSI goal rounds under " Karl Mehltretter
2026-09-15  7:04   ` KunWu Chan
2026-09-15 21:31     ` Karl Mehltretter [this message]
2026-09-16  0:21   ` SJ Park

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