Subject: Re: [RFC][PATCH] Runtime switching of the idle function [take 2]
From: john stultz <johnstul@us.ibm.com>
To: Andi Kleen <ak@suse.de>
Cc: Lee Revell <rlrevell@joe-job.com>, "Brown, Len" <len.brown@intel.com>,
       Nick Piggin <nickpiggin@yahoo.com.au>, Ingo Molnar <mingo@elte.hu>,
       Steven Rostedt <rostedt@goodmis.org>, Andrew Morton <akpm@osdl.org>,
       acpi-devel@lists.sourceforge.net, nando@ccrma.Stanford.EDU,
       linux-kernel@vger.kernel.org, paulmck@us.ibm.com, kr@cybsft.com,
       tglx@linutronix.de, pluto@agmk.net, john.cooper@timesys.com,
       bene@linutronix.de, dwalker@mvista.com, trini@kernel.crashing.org,
       george@mvista.com, Vojtech Pavlik <vojtech@suse.cz>
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Date: Tue, 29 Nov 2005 18:19:41 -0800
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On Wed, 2005-11-30 at 02:58 +0100, Andi Kleen wrote:
> > > Then you're likely running 32bit. It doesn't use vsyscall gettimeofday
> > > yet, which makes it slower. 64bit would.
> > 
> > Yes, I am.  So it sounds like vsyscall gettimeofday for i386 is in the
> > works?
> 
> John Stultz used to have patches for it, but for some reason he never
> pushed them into mainline. 

Unfortunately it was a pretty ugly patch. Correctness issues with the
existing code have kept focused on my timekeeping rework, however I have
kept it in mind, and I do have a i386 vsyscall gtod patch that applies
ontop of my tod work. I've been maintaining it on the side while I focus
on the core code, but it is much cleaner now. For fun I'll try to
remember to send it out with the next release.

> On i386 it unfortunately needs adding
> a test and branch to the syscall path to be 100% ABI compatible, but I 
> doubt that was the reason he dropped it.

Yea, I didn't know enough about the VDSO/unwind bits to get it to do the
right thing w/ glibc, so that bit was pretty hackish. I'll still need
some help on this bit to make it really something that could be
included.

thanks
-john


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