linux-kernel - Re: [PATCH 5/8] x86: Add IRQ_TIME

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Date:	Fri, 15 Oct 2010 16:38:31 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Venkatesh Pallipadi <venki@...gle.com>
Cc:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	linux-kernel@...r.kernel.org, Paul Turner <pjt@...gle.com>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH 5/8] x86: Add IRQ_TIME_ACCOUNTING in x86 -v4

On Mon, 2010-10-04 at 17:03 -0700, Venkatesh Pallipadi wrote:
> @@ -801,6 +805,7 @@ void mark_tsc_unstable(char *reason)
>         if (!tsc_unstable) {
>                 tsc_unstable = 1;
>                 sched_clock_stable = 0;
> +               disable_sched_clock_irqtime();
>                 printk(KERN_INFO "Marking TSC unstable due to %s\n", reason);
>                 /* Change only the rating, when not registered */
>                 if (clocksource_tsc.mult) 

I think we can be less strict that this and keep it enabled for
everything with constant tsc and nonstop tsc.

Since we're using it strictly per-cpu the cross-cpu sync isn't really
important, all we need it to know the per-cpu value doesn't go all
screwy on us.


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