linux-kernel - Re: [PATCH 7/7] selftests/proc: Remove idle time monotonicity assertions

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Message-ID: <Y/PVD58nzv8gDhFL@p183>
Date:   Mon, 20 Feb 2023 23:16:15 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Wei Li <liwei391@...wei.com>,
        Mirsad Goran Todorovac <mirsad.todorovac@....unizg.hr>,
        Yu Liao <liaoyu15@...wei.com>, Hillf Danton <hdanton@...a.com>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 7/7] selftests/proc: Remove idle time monotonicity
 assertions

On Mon, Feb 20, 2023 at 01:41:29PM +0100, Frederic Weisbecker wrote:
> Due to broken iowait task counting design (cf: comments above
> get_cpu_idle_time_us() and nr_iowait()), it is not possible to provide
> the guarantee that /proc/stat or /proc/uptime display monotonic idle
> time values.

Those test uptime _and_ idle time? You aren't sacking uptime, right?

>  delete mode 100644 tools/testing/selftests/proc/proc-uptime-001.c
>  delete mode 100644 tools/testing/selftests/proc/proc-uptime-002.c