From: Andi Kleen <andi@firstfloor.org>
To: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>, Pavel Machek <pavel@suse.cz>,
Rusty Russell <rusty@rustcorp.com.au>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jack Steiner <steiner@sgi.com>, "H. Peter Anvin" <hpa@zytor.com>,
Richard Purdie <rpurdie@rpsys.net>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/1] SGI X86 UV: Provide a System Activity Indicator driver
Date: Fri, 24 Oct 2008 20:12:38 +0200 [thread overview]
Message-ID: <87mygt9815.fsf@basil.nowhere.org> (raw)
In-Reply-To: <4901BF30.3090708@sgi.com> (Mike Travis's message of "Fri, 24 Oct 2008 05:27:28 -0700")
Mike Travis <travis@sgi.com> writes:
>
> I do use the timer mechanism (once per second) to update the scir state.
> Unfortunately, the state is *always* not idle during the timer callback
> (since we are actively executing), so I needed some way of knowing the
> idle state prior to the timer callback.
The idle thread always has pid 0. So if the timer sees current->pid == 0
it interrupted idle.
But sampling only once a second would be presumably not very accurate.
You could just check the per cpu statistics the kernel keeps
anyways in the timer.
I agree with Ingo that this doesn't belong in a idle notifier.
-Andi
--
ak@linux.intel.com
next prev parent reply other threads:[~2008-10-24 18:12 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-24 11:19 [PATCH 1/1] SGI X86 UV: Provide a System Activity Indicator driver Mike Travis
2008-10-24 12:01 ` Pavel Machek
2008-10-24 12:05 ` Ingo Molnar
2008-10-24 12:27 ` Mike Travis
2008-10-24 18:12 ` Andi Kleen [this message]
2008-10-24 22:18 ` Mike Travis
2008-10-24 22:24 ` Mike Travis
2008-10-27 11:42 ` Ingo Molnar
2008-10-27 14:38 ` Mike Travis
2008-10-27 14:51 ` [PATCH 1/1] SGI x86 UV: Update SCIR driver to use idle_cpu function Mike Travis
2008-10-27 18:06 ` Ingo Molnar
2008-10-27 18:46 ` [PATCH 1/1] SGI x86 UV: Use raw_smp_processor_id Mike Travis
2008-10-25 6:56 ` [PATCH 1/1] SGI X86 UV: Provide a System Activity Indicator driver Andi Kleen
2008-10-27 15:12 ` Mike Travis
2008-10-27 11:36 ` Ingo Molnar
2008-10-27 11:43 ` Ingo Molnar
2008-10-24 12:14 ` Mike Travis
-- strict thread matches above, loose matches on Subject: below --
2008-09-19 14:37 [PATCH 0/1] " Mike Travis
2008-09-19 14:37 ` [PATCH 1/1] " Mike Travis
2008-09-22 11:48 ` Ingo Molnar
2008-09-22 14:42 ` Mike Travis
2008-09-28 19:42 ` Pavel Machek
2008-10-01 18:15 ` Mike Travis
2008-10-01 19:41 ` Mike Travis
2008-10-02 8:37 ` Pavel Machek
2008-10-02 14:33 ` Mike Travis
2008-09-22 14:47 ` Mike Travis
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