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SubjectRe: [PATCH] PM / suspend: measure the time of filesystem syncing
On Sun 2019-02-03 13:20:07, 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.

Do we really need this functionality?

As you explained, developers can already use next timestamp or
ftrace... and this is really not that interesting number.

Pavel

> Signed-off-by: Harry Pan <harry.pan@intel.com>
> ---
> kernel/power/suspend.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 0bd595a0b610..f3b7c64f2242 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, end, elapsed;
> + unsigned int elapsed_msecs;
>
> trace_suspend_resume(TPS("suspend_enter"), state, true);
> if (state == PM_SUSPEND_TO_IDLE) {
> @@ -570,9 +572,14 @@ static int enter_state(suspend_state_t state)
>
> #ifndef CONFIG_SUSPEND_SKIP_SYNC
> trace_suspend_resume(TPS("sync_filesystems"), 0, true);
> + start = ktime_get_boottime();
> pr_info("Syncing filesystems ... ");
> ksys_sync();
> - pr_cont("done.\n");
> + end = ktime_get_boottime();
> + elapsed = ktime_sub(end, start);
> + elapsed_msecs = ktime_to_ms(elapsed);
> + 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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