linux-kernel - Re: [PATCH] x86: Reduce the default HZ value

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Date:	Thu, 7 May 2009 13:55:08 -0400 (EDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Peter Zijlstra <peterz@...radead.org>
cc:	Alok Kataria <akataria@...are.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	the arch/x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"alan@...rguk.ukuu.org.uk" <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] x86: Reduce the default HZ value

On Thu, 7 May 2009, Peter Zijlstra wrote:

> > If there is a single process running on a processor and no other process
> > is contending then there is no need to do involuntary preemption.
>
> Sure, and CONFIG_SCHED_HRTICK does that, the trick is getting it to not
> hurt others.

If other processors are scheduled on the processor then an IPI could
notify the scheduler over there to start timer interrupts for preemption
again.

I still see timer interrupts ongoing even with CONFIG_SCHED_HRTICK.

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