On 10/09/2013 09:35 PM, 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.
Good point. I misunderstood the patch and thought it was an issue that the statistics are never cleared even if the collection was disabled, but looking closer I see we clear on enable (if we were disabled). So yes, this change doesn't seem right. > Instead of this change I'd suggest adding a 'status' line, with two > outputs: > > Status: collection active > > Status: collection disabled Agreed. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
