linux-kernel - Re: [1/3] Bugfix: Don't use the TSC in sched

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Message-ID: <3d8471ca0703041033v689b51dfuba0b09fc979d7698@mail.gmail.com>
Date:	Sun, 4 Mar 2007 19:33:06 +0100
From:	"Guillaume Chazarain" <guichaz@...il.com>
To:	"Andi Kleen" <ak@...e.de>
Cc:	"Ingo Molnar" <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [1/3] Bugfix: Don't use the TSC in sched_clock if unstable

2007/3/4, Andi Kleen <ak@...e.de>:

> On what hardware?

Pentium M 798 MHz -> 2GHz

> And how many frequency transitions do you have per second?

10 in a kernel compile exhibiting audio skips.

Anyway, the "Clocksource tsc unstable (delta = -263211549 ns)" line
in the dmesg I attached to the previous mail confirms IMHO that my
TSC is too unstable for scheduling purpose.

15 minutes after booting, including a kernel compile halted on the
first audio skip, I have this in
/sys/devices/system/cpu/cpu0/cpufreq/stats/trans_table

   From  :    To
         :   1995000   1596000   1330000   1064000    798000
  1995000:         0        67       101       128       367
  1596000:        20         0         3         3        41
  1330000:        21         0         0        10        73
  1064000:        30         0         0         0       111
   798000:       592         0         0         0         0

Nothing alarming I presume.

Thanks.

-- 
Guillaume

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