From: Andi Kleen <andi@firstfloor.org>
To: Vasily Khoruzhick <anarsoul@gmail.com>
Cc: Venkatesh Pallipadi <venki@google.com>,
intel-gfx@lists.freedesktop.org,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: Interrupt latency on some 945GM platforms
Date: Tue, 14 Sep 2010 11:55:00 +0200 [thread overview]
Message-ID: <87tyls7iq3.fsf@basil.nowhere.org> (raw)
In-Reply-To: <201009141109.41596.anarsoul@gmail.com> (Vasily Khoruzhick's message of "Tue, 14 Sep 2010 11:09:36 +0300")
Vasily Khoruzhick <anarsoul@gmail.com> writes:
>> Whats the clockevent in this case ("Tick Device" section of
>> /proc/timer_list). clocksource= option only changes the clocksource used
>> to maintain
>> timeofday. But, timer interrupt (clockevent) source will not change.
>> Wondering how just the clocksource change is making the diff here..
>>
>> Also, if clocksource tsc has a higher rating than HPET. The reason
>> HPET is getting used as clocksource in the first place seems to be due
>> to TSC is not a dependable clocksource on this platform (may be it
>> stops in C3). So, I am not sure forcing it to tsc will be a good
>> thing. May be clocksource=acpi_pm is a better thing to try.
>>
>> Thanks,
>> Venki
>
> I investigated it a bit and found out that single nohz=off option helps. Just
> changing clocksource doesn't help, but it works smoothly with any clocksource
> with nohz=off. So, it seems that something wrong with intel driver while
> system is in tickless mode.
It could be simply that nohz=off prevents the system from
going into lower idle states and it is related to that.
You could test this theory by running with processor.max_cstate=1
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
prev parent reply other threads:[~2010-09-14 9:55 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <201009132336.17310.anarsoul@gmail.com>
[not found] ` <20100913134441.762001f7@jbarnes-desktop>
[not found] ` <201009140010.14783.anarsoul@gmail.com>
2010-09-13 21:19 ` Interrupt latency on some 945GM platforms Jesse Barnes
2010-09-13 21:41 ` Vasily Khoruzhick
2010-09-13 21:46 ` Jesse Barnes
2010-09-13 21:52 ` Vasily Khoruzhick
2010-09-13 21:59 ` Jesse Barnes
2010-09-13 22:03 ` Vasily Khoruzhick
2010-09-14 0:55 ` Venkatesh Pallipadi
2010-09-14 8:09 ` Vasily Khoruzhick
2010-09-14 9:52 ` Thomas Gleixner
2010-09-14 12:29 ` Vasily Khoruzhick
2010-09-14 22:41 ` Sitsofe Wheeler
2010-09-15 7:07 ` Vasily Khoruzhick
2010-09-16 15:03 ` Vasily Khoruzhick
2010-09-16 18:07 ` Thomas Gleixner
2010-09-16 18:30 ` Vasily Khoruzhick
2010-09-16 18:42 ` Vasily Khoruzhick
2010-09-16 18:50 ` Thomas Gleixner
2010-09-16 20:06 ` Vasily Khoruzhick
2010-09-24 19:39 ` Jesse Barnes
2010-09-24 19:48 ` Vasily Khoruzhick
2010-09-24 19:51 ` Jesse Barnes
2010-09-26 10:53 ` Stefan Biereigel
2010-09-27 0:46 ` Shaohua Li
2010-09-27 5:45 ` Stefan Biereigel
2010-09-27 11:41 ` Vasily Khoruzhick
2010-09-27 21:18 ` Vasily Khoruzhick
2010-09-25 10:25 ` Paolo Ornati
2010-09-17 9:02 ` [Intel-gfx] " Simon Farnsworth
2010-09-17 16:30 ` Jesse Barnes
2010-09-17 12:50 ` Vasily Khoruzhick
2010-09-21 18:26 ` Paolo Ornati
2010-09-21 22:56 ` Jesse Barnes
2010-09-22 5:57 ` Vasily Khoruzhick
2010-09-23 18:21 ` Paolo Ornati
2010-09-25 10:28 ` Paolo Ornati
2010-10-16 15:54 ` [Intel-gfx] Interrupt latency on some 945GM platforms -- and TCP/IP silent data corruption? Paolo Ornati
2010-09-24 18:41 ` Interrupt latency on some 945GM platforms Jesse Barnes
2010-09-14 9:55 ` Andi Kleen [this message]
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