From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Rob <roblinux@gmail.com>,
linux-kernel@vger.kernel.org, "Brown, Len" <lenb@kernel.org>
Subject: Re: TSC as clocksource
Date: Mon, 10 Jan 2011 14:54:45 +0100 (CET) [thread overview]
Message-ID: <alpine.LFD.2.00.1101101452290.12146@localhost6.localdomain6> (raw)
In-Reply-To: <1294667092.11896.0.camel@laptop>
On Mon, 10 Jan 2011, Peter Zijlstra wrote:
> On Mon, 2011-01-10 at 09:54 +1100, Rob wrote:
> > Want to use TSC as clocksource
> > have a Intel Core2 Duo with constant_tsc flag
> > TSC should be stable at C1 + C2, it is debatable whether C3 is stable
> >
> > Using processor.max_cstate=2 to use only C1 + C2 changes nothing, still get
> > Monitor-Mwait will be used to enter C-3 state
> > there should be checks before this is forced
We unconditinally set TSC unstable for anything > C1. The reason is
that we had a lot of troubles with BIOSes which advertise C2, but in
fact implement C3. Unfortunately we can't verify that.
Thanks,
tglx
next prev parent reply other threads:[~2011-01-10 13:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-09 22:54 TSC as clocksource Rob
2011-01-10 13:44 ` Peter Zijlstra
2011-01-10 13:54 ` Thomas Gleixner [this message]
2011-01-10 17:43 ` Len Brown
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