* Dong Zhu <bluezhud...@gmail.com> wrote:
> Hi Ingo and John,
>
> On Thu, Oct 10, 2013 at 06:35:19AM +0200, Ingo Molnar wrote:
> >
> > * Dong Zhu <bluezhud...@gmail.com> wrote:
> >
> > > From f41628c61d8a9172677ba33a55b61e37ce28f7a6 Mon Sep 17 00:00:00 2001
> > > From: Dong Zhu <bluezhud...@gmail.com>
> > > Date: Thu, 10 Oct 2013 10:38:13 +0800
> > >
> > > When we stop timer statistics collection (via echo 0 >
> > > /proc/timers_stats), the statistics data is still exported as if it were
> > > correct, which can cause applicaitons to misuse the statistics.
> >
> > What misuse do you mean?
> >
> > > This patch resets the statistics when we stop collecting them, to avoid
> > > this problem.
> >
> > Well, this loses the handy 'snapshot' property of /proc/timer_stats.
> > Before this change one could do:
> >
> > echo 1 > /proc/timers_stats
> > sleep 60 # run system workload
> > echo 0 > /proc/timers_stats
> >
> > and examine the 1-minute collection result without it changing. Your
> > change, if I understand it correctly, zeroes it all out.
>
> Yes, I am wrong about it. Thanks for pointing this out and pretty sorry
> for confusing you John.
>
> >
> > Instead of this change I'd suggest adding a 'status' line, with two
> > outputs:
> >
> > Status: collection active
> >
> > Status: collection disabled
> >
>
> Agree, I modified this patch and resubmited it again, Could you help
> reviewing it again ? Thanks !
>
> From 263c40abea8011c82582b2d671ae783b26f44bd5 Mon Sep 17 00:00:00 2001
> From: Dong Zhu <bluezhud...@gmail.com>
> Date: Thu, 10 Oct 2013 13:46:08 +0800
>
> We can enable|disable timer statistics collection (via echo [1|0] >
> /proc/timers_stats), this patch adds a 'status' line to display the
> current timer collection status.
>
> Signed-off-by: Dong Zhu <bluezhud...@gmail.com>
> ---
> kernel/time/timer_stats.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c
> index 0b537f2..bac5e91 100644
> --- a/kernel/time/timer_stats.c
> +++ b/kernel/time/timer_stats.c
> @@ -303,6 +303,10 @@ static int tstats_show(struct seq_file *m, void *v)
> if (atomic_read(&overflow_count))
> seq_printf(m, "Overflow: %d entries\n",
> atomic_read(&overflow_count));
> + if (timer_stats_active)
> + seq_puts(m, "Status: collection active\n");
> + else
> + seq_puts(m, "Status: collection disabled\n");
I suspect we could do something like:
seq_printf("Status: collection %s\n", timer_stats_active ? "enabled" :
"disabled");
and save a bit of kernel image size?
Also, please bump up the version to v0.3, to give parsers a chance.
Otherwise it looks good to me.
Thanks,
Ingo
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