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Message-ID: <16761.42743.34328.919506@cargo.ozlabs.ibm.com>
Date: Sat, 23 Oct 2004 10:33:59 +1000
From: Paul Mackerras <paulus@samba.org>
To: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       Linus Torvalds <torvalds@osdl.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] pmac_cpufreq msleep cleanup/fixes
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	<1098484616.6028.80.camel@gaston>
	<Pine.LNX.4.58.0410221552320.2101@ppc970.osdl.org>
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	<20041022234344.GI18906@us.ibm.com>
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Nishanth Aravamudan writes:

> Looks good to me... And makes quite a bit of sense, after I thought
> about it. Does feel a little hacky, but I don't see a slicker way around
> the problem...

We would need a platform-specific function to tell us how long until
the next jiffy to do any better, I think, and even then it would only
make much of a difference if HZ was significantly smaller than 1000.

We could do the how-long-until-next-jiffy function quite easily and
quickly on ppc and ppc64, just by reading the decrementer register and
scaling it.  I don't know about other architectures.  But if we are
mostly using HZ=1000 there doesn't seem to be much point.

Paul.
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