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Date: Sun, 29 Jan 2012 10:25:46 +0200
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Subject: Re: [v7 0/8] Reduce cross CPU IPI interference
From: Gilad Ben-Yossef <gilad@benyossef.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-kernel@vger.kernel.org, Christoph Lameter <cl@linux.com>,
        Chris Metcalf <cmetcalf@tilera.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, linux-mm@kvack.org,
        Pekka Enberg <penberg@kernel.org>, Matt Mackall <mpm@selenic.com>,
        Sasha Levin <levinsasha928@gmail.com>, Rik van Riel <riel@redhat.com>,
        Andi Kleen <andi@firstfloor.org>, Mel Gorman <mel@csn.ul.ie>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>, Avi Kivity <avi@redhat.com>,
        Michal Nazarewicz <mina86@mina86.com>,
        Kosaki Motohiro <kosaki.motohiro@gmail.com>,
        Milton Miller <miltonm@bga.com>
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On Thu, Jan 26, 2012 at 5:19 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>
> On Thu, 2012-01-26 at 12:01 +0200, Gilad Ben-Yossef wrote:
> > Gilad Ben-Yossef (8):
> >   smp: introduce a generic on_each_cpu_mask function
> >   arm: move arm over to generic on_each_cpu_mask
> >   tile: move tile to use generic on_each_cpu_mask
> >   smp: add func to IPI cpus based on parameter func
> >   slub: only IPI CPUs that have per cpu obj to flush
> >   fs: only send IPI to invalidate LRU BH when needed
> >   mm: only IPI CPUs to drain local pages if they exist
>
> These patches look very nice!
>
> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
>

Thank you :-)

If this is of interest, I keep a list tracking global IPI and global
task schedulers sources in the core kernel here:
https://github.com/gby/linux/wiki.

I plan to visit all these potential interference source to see if
something can be done to lower their effect on
isolated CPUs over time.

>
> >   mm: add vmstat counters for tracking PCP drains
> >
> I understood from previous postings this patch wasn't meant for
> inclusion, if it is, note that cpumask_weight() is a potentially very
> expensive operation.

Right. The only purpose of the patch is to show the usefulness
of the previous patch in the series. It is not meant for mainline.

Thanks,
Gilad



--
Gilad Ben-Yossef
Chief Coffee Drinker
gilad@benyossef.com
Israel Cell: +972-52-8260388
US Cell: +1-973-8260388
http://benyossef.com

"Unfortunately, cache misses are an equal opportunity pain provider."
-- Mike Galbraith, LKML