From: Andi Kleen <ak@suse.de>
To: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
Christopher Friesen <cfriesen@nortel.com>,
Russell King <rmk+lkml@arm.linux.org.uk>,
linux-kernel@vger.kernel.org
Subject: Re: sched_clock() uses are broken
Date: Wed, 3 May 2006 11:16:09 +0200 [thread overview]
Message-ID: <200605031116.09428.ak@suse.de> (raw)
In-Reply-To: <1146647462.7440.12.camel@homer>
On Wednesday 03 May 2006 11:11, Mike Galbraith wrote:
> On Wed, 2006-05-03 at 09:40 +0200, Andi Kleen wrote:
> > On Wednesday 03 May 2006 09:09, Mike Galbraith wrote:
> >
> > > Given that most people are going to end up using the pm_timer anyway, I
> > > don't see the point of even having a sched_clock(). If it's jiffy
> > > resolution, it's useless. If it's wildly inaccurate (as it is in the
> > > SMP case, monotonicity issues aside) it's more than useless.
> >
> > For sched_clock TSC is always used and it's fine - sched_clock
> > doesn't require the guarantees that make TSC often useless otherwise
>
> Regrettable, that's not true.
Hmm, maybe I'm thinking too much x86-64. At least on x86-64 it's true.
I don't see a big reason to not do this on i386 either, except
on systems that truly don't have a TSC (386/486)
Ok i suppose if you don't want cruft you can always go to 64bit @)
-Andi
next prev parent reply other threads:[~2006-05-03 9:16 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-02 13:29 sched_clock() uses are broken Russell King
2006-05-02 14:21 ` Nick Piggin
2006-05-02 16:43 ` Andi Kleen
2006-05-02 16:50 ` Russell King
2006-05-02 17:01 ` Andi Kleen
2006-05-02 17:18 ` Nicolas Pitre
2006-05-02 18:55 ` Russell King
2006-05-02 19:05 ` Nicolas Pitre
2006-05-02 19:08 ` Russell King
2006-05-02 19:23 ` Nicolas Pitre
2006-05-02 21:35 ` Russell King
2006-05-02 17:15 ` Nicolas Pitre
2006-05-04 3:50 ` George Anzinger
2006-05-04 14:18 ` Nicolas Pitre
2006-05-02 16:54 ` Christopher Friesen
2006-05-02 16:59 ` Andi Kleen
2006-05-02 17:07 ` Nick Piggin
2006-05-03 7:09 ` Mike Galbraith
2006-05-03 7:40 ` Andi Kleen
2006-05-03 9:11 ` Mike Galbraith
2006-05-03 9:16 ` Andi Kleen [this message]
2006-05-03 9:31 ` Mike Galbraith
2006-05-07 12:33 ` Nick Piggin
2006-05-07 12:43 ` Russell King
2006-05-07 12:56 ` Nick Piggin
2006-05-07 13:00 ` Nick Piggin
2006-05-07 13:18 ` Russell King
2006-05-07 13:30 ` Nick Piggin
2006-05-07 13:55 ` Russell King
2006-05-07 14:04 ` Nick Piggin
2006-05-07 16:03 ` Andi Kleen
2006-05-07 16:53 ` Russell King
2006-05-07 17:52 ` Mike Galbraith
2006-05-07 17:37 ` Mike Galbraith
2006-05-07 17:32 ` Mike Galbraith
2006-05-08 4:14 ` Mike Galbraith
2006-05-08 4:37 ` Mike Galbraith
2006-05-08 4:46 ` Nick Piggin
2006-05-08 5:24 ` Mike Galbraith
2006-05-08 5:30 ` Nick Piggin
2006-05-04 20:02 ` Florian Paul Schmidt
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