linux-kernel - Re: [PATCH 2/2][RFC v2] PM-runtime: change the tracepoints to cover all usage

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Date:   Mon, 8 Jun 2020 09:50:39 +0200
From:   Michal Miroslaw <mirq-linux@...e.qmqm.pl>
To:     Chen Yu <yu.c.chen@...el.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2][RFC v2] PM-runtime: change the tracepoints to cover
 all usage_count

On Mon, Jun 08, 2020 at 03:42:15PM +0800, Chen Yu wrote:
> Commit d229290689ae ("PM-runtime: add tracepoints for usage_count changes")
> has added some tracepoints to monitor the change of runtime usage, and
> there is something to improve:
> 1. There are some places that adjust the usage count have not
>    been traced yet. For example, pm_runtime_get_noresume() and
>    pm_runtime_put_noidle()
> 2. The change of the usage count will not be tracked if decreased
>    from 1 to 0.
> 
> This patch intends to adjust the logic to be consistent with the
> change of usage_counter, that is to say, only after the counter has
> been possibly modified, we record it. Besides, all usage changes will
> be shown using rpm_usage even if included by other trace points.
> And these changes has helped track down the e1000e runtime issue.
> 
> Signed-off-by: Chen Yu <yu.c.chen@...el.com>
> ---
> v2: According to Michal's suggestion, adjust the commit log
>     to better describe the meaning of this patch.
> --
>  drivers/base/power/runtime.c | 38 +++++++++++++++++++++++-------------
>  1 file changed, 24 insertions(+), 14 deletions(-)
[...]

Reviewed-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>