Date:   Tue, 14 Mar 2023 20:58:18 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Song Liu <song@kernel.org>
Cc:     linux-kernel@vger.kernel.org, kernel-team@meta.com,
        Namhyung Kim <namhyung@kernel.org>
Subject: Re: [PATCH v2] perf: fix perf_event_context->time
Message-ID: <20230314195818.GD273121@hirez.programming.kicks-ass.net>
References: <20230313171608.298734-1-song@kernel.org>
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On Mon, Mar 13, 2023 at 10:16:08AM -0700, Song Liu wrote:
> Time readers rely on perf_event_context->[time|timestamp|timeoffset] to get
> accurate time_enabled and time_running for an event. The difference between
> ctx->timestamp and ctx->time is the among of time when the context is not
> enabled. __update_context_time(ctx, false) is used to increase timestamp,
> but not time. Therefore, it should only be called in ctx_sched_in() when
> EVENT_TIME was not enabled.
> 
> Fixes: 09f5e7dc7ad7 ("perf: Fix perf_event_read_local() time")
> Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Acked-by: Namhyung Kim <namhyung@kernel.org>
> Signed-off-by: Song Liu <song@kernel.org>

Looks like I'm wearing another brown paper bag tonight..

Thanks!