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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Wed, 13 Feb 2019 00:35:37 +0100
Message-ID: <CAJZ5v0j3pDoLnxNqZRvNW8+hdBs_MLf22OsNivkBpcCG_if0DA@mail.gmail.com>
Subject: Re: [PATCH] PM / suspend: measure the time of filesystem syncing
To:     Harry Pan <harry.pan@intel.com>
Cc:     LKML <linux-kernel@vger.kernel.org>, Harry Pan <gs0622@gmail.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Pavel Machek <pavel@ucw.cz>, Len Brown <len.brown@intel.com>,
        Linux PM <linux-pm@vger.kernel.org>
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On Wed, Feb 13, 2019 at 12:21 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Wed, Feb 6, 2019 at 4:57 PM Harry Pan <harry.pan@intel.com> 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@intel.com>
> > ---
> >  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;
>
> You only need these two if CONFIG_SUSPEND_SKIP_SYNC is set, ->

s/set/unset/

Sorry for the confusion.