From: Peter Zijlstra <peterz@infradead.org>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Robin Holt <holt@sgi.com>, Dimitri Sivanich <sivanich@sgi.com>,
"linux-ia64@vger.kernel.org" <linux-ia64@vger.kernel.org>,
Greg KH <greg@kroah.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Gregory Haskins <ghaskins@novell.com>,
Nick Piggin <npiggin@suse.de>, Tony Luck <tony.luck@gmail.com>
Subject: RE: [PATCH] configure HAVE_UNSTABLE_SCHED_CLOCK for SGI_SN systems
Date: Tue, 06 Jan 2009 21:57:20 +0100 [thread overview]
Message-ID: <1231275441.11687.110.camel@twins> (raw)
In-Reply-To: <57C9024A16AD2D4C97DC78E552063EA35CB955B4@orsmsx505.amr.corp.intel.com>
On Tue, 2009-01-06 at 12:34 -0800, Luck, Tony wrote:
> > > All ia64 systems are potentially affected ... but perhaps you might
> > > never see the problem on most because the itc clocks are synced as close
> > > as s/w can get them when cpus are brought on line.
> >
> > Do you want Dimitri to resubmit with this set for all IA64 or leave it
> > as is?
>
> I'd like to understand the impact of turning on HAVE_UNSTABLE_SCHED_CLOCK
>
> It looks like both the i386_defconfig and x86_64_defconfig choose this,
> so at least ia64 will be hitting the well tested code paths
>
> Have the other architectures just not hit this yet? Or do they all have
> "stable" sched_clock() functions?
>
>
> sched_clock() seemed like such a straightforward thing to begin with. A
> quick & easy way to measure a time delta ON THE SAME CPU. I'm not at
> all sure why it has been co-opted for general time measurement.
It came from the complication of needing to tell a remote cpu's time due
to remote wakeups in the scheduler.
next prev parent reply other threads:[~2009-01-06 20:57 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-06 16:27 [PATCH] configure HAVE_UNSTABLE_SCHED_CLOCK for SGI_SN systems Dimitri Sivanich
2009-01-06 17:12 ` Greg KH
2009-01-06 20:15 ` Luck, Tony
2009-01-06 20:19 ` Robin Holt
2009-01-06 20:34 ` Luck, Tony
2009-01-06 20:57 ` Peter Zijlstra [this message]
2009-01-06 22:50 ` Robin Holt
2009-01-06 23:16 ` Peter Zijlstra
2009-01-07 3:00 ` Nick Piggin
2009-01-07 3:16 ` Jack Steiner
2009-01-07 7:28 ` Peter Zijlstra
2009-01-07 7:40 ` Nick Piggin
2009-01-07 9:43 ` Robin Holt
2009-01-07 9:53 ` Peter Zijlstra
2009-01-07 13:32 ` Dimitri Sivanich
2009-01-07 15:16 ` Peter Zijlstra
2009-01-15 18:48 ` Greg KH
2009-01-15 19:21 ` Luck, Tony
2009-01-22 19:04 ` Greg KH
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