linux-kernel - Re: 2.6.25-rc5-git6: Reported regressions from 2.6.24

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Date:	Fri, 21 Mar 2008 22:15:28 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Gabriel C <crazy@...galware.org>
cc:	Gabriel C <nix.or.die@...glemail.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	LKML <linux-kernel@...r.kernel.org>,
	Adrian Bunk <bunk@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Natalie Protasevich <protasnb@...il.com>,
	andi-bz@...stfloor.org, Ingo Molnar <mingo@...e.hu>
Subject: Re: 2.6.25-rc5-git6: Reported regressions from 2.6.24

On Fri, 21 Mar 2008, Gabriel C wrote:
> >>> Does that make any sense ?
> >> Not really. Can you please revert the reverted revert again and run
> >>
> >> http://people.redhat.com/mingo/time-warp-test/time-warp-test.c
> >>
> >> on your machine with all CPUs and HT enabled ?
> > 
> > Sure , doing so now.
> > 
> 
> Here the result on 2.6.25-rc6-00243-g028011e ( it was running 30++
> minutes the time I was away for food =) )
> ...
> 
>  4 CPUs, running 4 parallel test-tasks.
> checking for time-warps via:
> - read time stamp counter (RDTSC) instruction (cycle resolution)
> - gettimeofday (TOD) syscall (usec resolution)
> - clock_gettime(CLOCK_MONOTONIC) syscall (nsec resolution)
> 
> | 1.46 us, TSC-warps:0 | 16.01 us, TOD-warps:0 | 16.10 us, CLOCK-warps:0

Amazing. I never found a multi socket box where the TSC's were in sync.

So the rotating watchdog triggers for a yet to figure out reason.

Oh, now that the pm timer seems to work again, can you try the following:

apply the reverted patch again and let the box boot. At some point the
TSC is marked unstable and is replaced by acpi_pm clocksource.

What result does timewarp.c show in that situation ?

Thanks,
	tglx
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