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Date: Mon, 4 May 2026 10:08:32 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Minwoo Ahn <mwahn402@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
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	Jinkyu Jeong <jinkyu@yonsei.ac.kr>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] perf/core: Fix sampling period inconsistency across
 CPU migration
Message-ID: <20260504080832.GO3126523@noisy.programming.kicks-ass.net>
References: <20260429095134.10049-1-mwahn402@gmail.com>
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In-Reply-To: <20260429095134.10049-1-mwahn402@gmail.com>

On Wed, Apr 29, 2026 at 09:51:34AM +0000, Minwoo Ahn wrote:
> 
> When per-task software events are sampled, period_left is not
> managed consistently when task migration happens. The perf_event
> may observe a different hw_perf_event::period_left on the new CPU,
> breaking the sampling periodicity. Even if a task was near its
> sampling point, it would use a stale period_left after migration.

How? This is just vague words, not actually saying anything of
substance.

> Introduce struct perf_task_context as a per-task container to

How can you propose a solution to a non-defined problem?