From: Andi Kleen <ak@suse.de>
To: "Andreas Herrmann" <andreas.herrmann3@amd.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: limit mwait_idle to Intel CPUs
Date: Thu, 5 Apr 2007 17:37:17 +0200 [thread overview]
Message-ID: <200704051737.17157.ak@suse.de> (raw)
In-Reply-To: <20070405144442.GP6356@alberich.amd.com>
> > > This patch will enable default_idle for non-Intel
> > > CPUs even if mwait is supported.
> >
> > It would be better to clear MONITOR/MWAIT in the AMD specific
> > CPU initialize code than add workarounds everywhere else.
>
> Why is that?
> MONITOR/MWAIT is usable.
If it doesn't save power it's not usable imho.
> And I think this should
> be indicated by cpuinfo.
> It's just inappropriate to use it in pm_idle.
There are no other users anyways and user space can't use it.
Ok in theory you could add a X86_FEATURE_MWAIT_DOESNT_SAVE_POWER
and check that, but just clearing it seems simpler and equivalent.
What would perhaps make sense is to add a idle=mwait command
line option for this though. So that the benchmarkers who currently
use idle=poll could migrate to idle=mwait. That option would need
to check the real cpuid bit of course again, but that should be
easy enough.
-Andi
next prev parent reply other threads:[~2007-04-05 15:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-05 14:00 [PATCH] x86: limit mwait_idle to Intel CPUs Andreas Herrmann
2007-04-05 14:24 ` Andi Kleen
2007-04-05 14:44 ` Andreas Herrmann
2007-04-05 15:37 ` Andi Kleen [this message]
2007-04-05 16:20 ` Andreas Herrmann
2007-04-05 16:55 ` H. Peter Anvin
2007-04-05 17:06 ` Markus Rechberger
2007-04-05 17:36 ` H. Peter Anvin
2007-04-05 21:12 ` aherrman
2007-04-05 21:19 ` H. Peter Anvin
2007-04-05 17:05 ` Andi Kleen
2007-04-05 14:46 ` Langsdorf, Mark
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