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Message-Id: <200712072213.06530.nickpiggin@yahoo.com.au> Date: Fri, 7 Dec 2007 22:13:05 +1100 From: Nick Piggin <nickpiggin@...oo.com.au> To: Ingo Molnar <mingo@...e.hu> Cc: Stefano Brivio <stefano.brivio@...imi.it>, Robert Love <rml@...h9.net>, linux-kernel@...r.kernel.org, Dave Jones <davej@...hat.com>, "Rafael J. Wysocki" <rjw@...k.pl>, Michael Buesch <mb@...sch.de>, Thomas Gleixner <tglx@...utronix.de>, Andrew Morton <akpm@...ux-foundation.org>, Len Brown <lenb@...nel.org> Subject: Re: [PATCH] scheduler: fix x86 regression in native_sched_clock On Friday 07 December 2007 19:45, Ingo Molnar wrote: > * Stefano Brivio <stefano.brivio@...imi.it> wrote: > > This patch fixes a regression introduced by: > > > > commit bb29ab26863c022743143f27956cc0ca362f258c > > Author: Ingo Molnar <mingo@...e.hu> > > Date: Mon Jul 9 18:51:59 2007 +0200 > > > > This caused the jiffies counter to leap back and forth on cpufreq > > changes on my x86 box. I'd say that we can't always assume that TSC > > does "small errors" only, when marked unstable. On cpufreq changes > > these errors can be huge. > > ah, printk_clock() still uses sched_clock(), not jiffies. So it's not > the jiffies counter that goes back and forth, it's sched_clock() - so > this is a printk timestamps anomaly, not related to jiffies. I thought > we have fixed this bug in the printk code already: sched_clock() is a > 'raw' interface that should not be used directly - the proper interface > is cpu_clock(cpu). It's a single CPU box, so sched_clock() jumping would still be problematic, no? My patch should fix the worst cpufreq sched_clock jumping issue I think. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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