From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Stephen Hemminger <shemminger@vyatta.com>
Subject: Re: [PATCH] make refrigerator cold
Date: Wed, 23 Sep 2009 01:13:20 +0200
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Cc: Len Brown <len.brown@intel.com>, Matt Helsley <matthltc@us.ibm.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org
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On Tuesday 22 September 2009, Stephen Hemminger wrote:
> On Tue, 22 Sep 2009 21:54:09 +0200
> "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> 
> > On Tuesday 22 September 2009, Stephen Hemminger wrote:
> > > By marking it cold, then the code path in kernel thread 
> > > usage of try_to_freeze() that is normally used be
> > > selected.
> > 
> 
> In the code for try_to_freeze(), for optimization, it might
> help to tell the compiler to not favor the code path where
> the refigrator is being called.
> 
> Another way to do the same thing would be to do.
>    if (unlikely(freezing(current))) {
> 	refrigerator();
> 	return 1;
>    } else
> 	return 0;
> 
> or build unlikely into the freezing function (see need_resched).
> 
> I saw this by trying to minimize the number of intstructions
> in pktgen which is a special case.

OK, thanks.

Will it be fine with you if I add the patch to the suspend-2.6 tree with the
above information in the changelog?

Rafael
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