From: Andi Kleen <ak@suse.de>
To: "Guillaume Chazarain" <guichaz@gmail.com>
Cc: "Ingo Molnar" <mingo@elte.hu>, linux-kernel@vger.kernel.org
Subject: Re: [1/3] Bugfix: Don't use the TSC in sched_clock if unstable
Date: Sun, 4 Mar 2007 15:37:27 +0100 [thread overview]
Message-ID: <200703041537.27581.ak@suse.de> (raw)
In-Reply-To: <3d8471ca0703031341l1768fe7rccf40712e452ea09@mail.gmail.com>
On Saturday 03 March 2007 22:41, Guillaume Chazarain wrote:
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f9690982b8c2f9a2c65acdc113e758ec356676a3
> caused a regression by letting sched_clock use the TSC even when cpufreq
> disabled it. This caused scheduling weirdnesses.
What weirdnesses? Did you actually see any? Hard data please.
I don't like this because right now it will effectively disable TSC use
on anything with pstate invariant TSC and using cpufreq: that is all
modern AMD systems. This is IMHO a serious bug in the timer subsystem which
I intend to fix.
Also I don't see where your instability should come from. AFAIK
there are only minor hickups in the result which shouldn't be a problem IMHO.
-Andi
next prev parent reply other threads:[~2007-03-04 14:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-03 21:41 [1/3] Bugfix: Don't use the TSC in sched_clock if unstable Guillaume Chazarain
2007-03-04 14:37 ` Andi Kleen [this message]
[not found] ` <3d8471ca0703040741h4eff73a3wd67d648d52497e34@mail.gmail.com>
2007-03-04 17:25 ` Andi Kleen
2007-03-04 18:33 ` Guillaume Chazarain
2007-03-04 23:28 ` Andi Kleen
2007-03-05 0:15 ` Guillaume Chazarain
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