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Date: Tue, 19 Aug 2008 11:22:23 -0700
From: Greg KH <gregkh@suse.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, Justin Madru <jdm64@gawab.com>,
       lkml <linux-kernel@vger.kernel.org>,
       Michal Januszewski <spock@gentoo.org>,
       Antonino Daplas <adaplas@gmail.com>, Rafael Wysocki <rjw@sisk.pl>,
       Romano Giannetti <romano.giannetti@gmail.com>,
       Adrian Bunk <bunk@kernel.org>,
       Jeremy Nickurak <kernel-bugs@atrus.rifetech.com>
Subject: Re: Backport hr-tick fix into .25/.26
Message-ID: <20080819182222.GA25576@suse.de>
References: <48A9BDC0.9070800@gawab.com> <20080819003110.GH9914@elte.hu> <1219127296.10800.357.camel@twins> <20080819092543.GD28713@elte.hu> <1219138380.10800.376.camel@twins>
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On Tue, Aug 19, 2008 at 11:33:00AM +0200, Peter Zijlstra wrote:
> On Tue, 2008-08-19 at 11:25 +0200, Ingo Molnar wrote:
> > * Peter Zijlstra <peterz@infradead.org> wrote:
> > 
> > > On Tue, 2008-08-19 at 02:31 +0200, Ingo Molnar wrote:
> > > > * Justin Madru <jdm64@gawab.com> wrote:
> > > > 
> > > > > This commit introduced the bug.
> > > > > commit 8f4d37ec073c17e2d4aa8851df5837d798606d6f
> > > > > sched: high-res preemption tick
> > > > 
> > > > > And this one fixed it
> > > > >
> > > > > commit 31656519e132f6612584815f128c83976a9aaaef
> > > > > sched, x86: clean up hrtick implementation
> > > > 
> > > > hm, the backport of 31656519 is a bit intrusive.
> > > > 
> > > > find below is an (untested!) version of it - i havent even build-tested 
> > > > it. Does it work for you? But this is Greg's call really.
> > > > 
> > > 
> > > It largely depends on all the new IPI stuff that went into 27 as well, 
> > > so I'd be surprised if its easily backportable..
> > 
> > ah, i see. How about a simple patch then that disables hrtick [given 
> > that it's now fixed .27 but the fix is too intrusive to backport]? Would 
> > that be too risky for -stable?
> 
> That's just flipping sched_feat(HRTICK) to 0 by default.

That sounds reasonable, I'll take a patch for that for -stable :)

thanks,

greg k-h