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Date: Mon, 18 Feb 2002 11:04:22 -0800
From: george anzinger <george@mvista.com>
Organization: Monta Vista Software
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To: "H. Peter Anvin" <hpa@zytor.com>
CC: linux-kernel@vger.kernel.org, "Grover, Andrew" <andrew.grover@intel.com>
Subject: Re: Missed jiffies
In-Reply-To: <3C6E77DE.70FE49DF@rwii.com> <3C6E833F.1A888B3C@mvista.com> <a4pbvi$iq2$1@cesium.transmeta.com>
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"H. Peter Anvin" wrote:
> 
> Followup to:  <3C6E833F.1A888B3C@mvista.com>
> By author:    george anzinger <george@mvista.com>
> In newsgroup: linux.dev.kernel
> >
> > One of the nasty problems, especially with machines such as yours (i.e.
> > lap tops), is the fact that TSC is NOT clocked at a fixed rate.  It is
> > affected by throttling (reduced in 12.5% increments) and by power
> > management.
> 
> If the TSC is affected by HLT, throttling, or C2 power management, the
> TSC is broken (as it is on Cyrix chips, for example.)  The TSC usually
> *is* affected by C3 power management, but the OS should be aware of
> C3.
> 
>         -hpa
Gosh I would LIKE to think this is true.  Could you give a reference?  I
believe Andrew Grover thinks that what I have stated is true.  If I am
wrong, it will make the high-res-timers MUCH more acceptable as the TSC
overhead is MUCH lower that the ACPI pm timer.

Do I have this right Andrew?
-- 
George           george@mvista.com
High-res-timers: http://sourceforge.net/projects/high-res-timers/
Real time sched: http://sourceforge.net/projects/rtsched/
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