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Message-ID: <20190206145322.GA31815@amd>
Date: Wed, 6 Feb 2019 15:53:22 +0100
From: Pavel Machek <pavel@....cz>
To: Harry Pan <harry.pan@...el.com>
Cc: LKML <linux-kernel@...r.kernel.org>, gs0622@...il.com,
rjw@...ysocki.net, len.brown@...el.com, linux-pm@...r.kernel.org
Subject: Re: [PATCH] PM / suspend: measure the time of filesystem syncing
On Wed 2019-02-06 22:42:57, Harry Pan wrote:
> This patch gives the reader an intuitive metric of the time cost by
> the kernel issuing a filesystem sync during suspend; although developer
> can guess by the timestamp of next log or enable the ftrace power event
> for manual calculation, this manner is easier to read and benefits the
> automatic script.
>
> v2: simplify the variables, apply the simplest form of ktime API.
>
> Signed-off-by: Harry Pan <harry.pan@...el.com>
NAK.
Pavel
> ---
> kernel/power/suspend.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 0bd595a0b610..87c0073f0c9d 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -550,6 +550,8 @@ static void suspend_finish(void)
> static int enter_state(suspend_state_t state)
> {
> int error;
> + ktime_t start;
> + unsigned int elapsed_msecs;
>
> trace_suspend_resume(TPS("suspend_enter"), state, true);
> if (state == PM_SUSPEND_TO_IDLE) {
> @@ -570,9 +572,12 @@ static int enter_state(suspend_state_t state)
>
> #ifndef CONFIG_SUSPEND_SKIP_SYNC
> trace_suspend_resume(TPS("sync_filesystems"), 0, true);
> + start = ktime_get();
> pr_info("Syncing filesystems ... ");
> ksys_sync();
> - pr_cont("done.\n");
> + elapsed_msecs = ktime_to_ms(ktime_sub(ktime_get(), start));
> + pr_cont("(elapsed %d.%03d seconds) done.\n", elapsed_msecs / 1000,
> + elapsed_msecs % 1000);
> trace_suspend_resume(TPS("sync_filesystems"), 0, false);
> #endif
>
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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