From: Gilad Ben-Yossef <gilad@benyossef.com>
To: Mel Gorman <mel@csn.ul.ie>
Cc: linux-kernel@vger.kernel.org, Chris Metcalf <cmetcalf@tilera.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Frederic Weisbecker <fweisbec@gmail.com>,
Russell King <linux@arm.linux.org.uk>,
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>,
Andrew Morton <akpm@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH v5 7/8] mm: Only IPI CPUs to drain local pages if they exist
Date: Sun, 8 Jan 2012 18:01:54 +0200 [thread overview]
Message-ID: <CAOtvUMezyvi1icpxo6YC5apJU-LZ5ns-RSeaL1q3CYw34AULFQ@mail.gmail.com> (raw)
In-Reply-To: <20120105155445.GC27881@csn.ul.ie>
On Thu, Jan 5, 2012 at 5:54 PM, Mel Gorman <mel@csn.ul.ie> wrote:
>
> On Mon, Jan 02, 2012 at 12:24:18PM +0200, Gilad Ben-Yossef wrote:
>
> > Tested by running "hackbench 400" on a 4 CPU x86 otherwise
> > idle VM and observing the difference between the number
> > of direct reclaim attempts that end up in drain_all_pages()
> > and those were more then 1/2 of the online CPU had any
> > per-cpu page in them, using the vmstat counters introduced
> > in the next patch in the series and using proc/interrupts.
> >
> > In the test sceanrio, this saved around 500 global IPIs.
> > After trigerring an OOM:
> >
> > $ cat /proc/vmstat
> > ...
> > pcp_global_drain 627
> > pcp_global_ipi_saved 578
> >
>
> This isn't 99% savings as you claim earlier but they are still great.
>
You are right of course, more like 92%. I did see test runs where the %
was 99% (which is were the 99% number came from) .I never saw it drop
below 90% for the specified test load.
I modified the description to read 90%+. I guess that is good enough.
> Thanks for doing the stats. Just to be clear, I didn't expect these
> stats to be merged, nor do I want them to. I wanted to be sure the patch
> was really behaving as advertised.
>
> Acked-by: Mel Gorman <mgorman@suse.de>
>
Of course, my pleasure and thanks for the review.
>
>
> > + for_each_online_cpu(cpu)
> > + for_each_populated_zone(zone) {
> > + pcp = per_cpu_ptr(zone->pageset, cpu);
> > + if (pcp->pcp.count)
> > + cpumask_set_cpu(cpu, cpus_with_pcps);
> > + else
> > + cpumask_clear_cpu(cpu, cpus_with_pcps);
> > + }
> > + on_each_cpu_mask(cpus_with_pcps, drain_local_pages, NULL, 1);
>
> As a heads-up, I'm looking at a candidate CPU hotplug patch that almost
> certainly will collide with this patch. If/when I get it fixed, I'll be
> sure to CC you so we can figure out what order the patches need to go
> in. Ordinarily it wouldn't matter but if this really is a CPU hotplug
> fix, it might also be a -stable candidate so it would need to go in
> before your patches.
No problem. I'm sending v6 right now because of unrelated changes Andrew M.
asked for. I'll be happy to re-base on top of CPU hotplug fixes later.
Thanks,
Gilad
--
Gilad Ben-Yossef
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gilad@benyossef.com
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prev parent reply other threads:[~2012-01-08 16:01 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1325499859-2262-1-git-send-email-gilad@benyossef.com>
2012-01-02 10:24 ` [PATCH v5 1/8] smp: Introduce a generic on_each_cpu_mask function Gilad Ben-Yossef
2012-01-03 7:51 ` Michal Nazarewicz
2012-01-03 8:12 ` Gilad Ben-Yossef
2012-01-03 8:57 ` Michal Nazarewicz
2012-01-03 22:26 ` Andrew Morton
2012-01-05 13:17 ` Michal Nazarewicz
2012-01-08 16:04 ` Gilad Ben-Yossef
2012-01-02 10:24 ` [PATCH v5 2/8] arm: Move arm over to generic on_each_cpu_mask Gilad Ben-Yossef
2012-01-02 10:24 ` [PATCH v5 3/8] tile: Move tile to use " Gilad Ben-Yossef
2012-01-02 10:24 ` [PATCH v5 4/8] smp: Add func to IPI cpus based on parameter func Gilad Ben-Yossef
2012-01-03 22:34 ` Andrew Morton
2012-01-08 16:09 ` Gilad Ben-Yossef
2012-01-02 10:24 ` [PATCH v5 5/8] slub: Only IPI CPUs that have per cpu obj to flush Gilad Ben-Yossef
2012-01-02 10:24 ` [PATCH v5 6/8] fs: only send IPI to invalidate LRU BH when needed Gilad Ben-Yossef
2012-01-02 10:24 ` [PATCH v5 7/8] mm: Only IPI CPUs to drain local pages if they exist Gilad Ben-Yossef
2012-01-03 17:45 ` KOSAKI Motohiro
2012-01-03 18:58 ` Gilad Ben-Yossef
2012-01-03 22:02 ` KOSAKI Motohiro
2012-01-05 14:20 ` Mel Gorman
2012-01-05 14:40 ` Russell King - ARM Linux
2012-01-05 15:24 ` Peter Zijlstra
2012-01-05 16:17 ` Mel Gorman
2012-01-05 16:35 ` Russell King - ARM Linux
2012-01-05 18:35 ` Paul E. McKenney
2012-01-05 22:21 ` Mel Gorman
2012-01-06 6:06 ` Srivatsa S. Bhat
2012-01-06 10:46 ` Mel Gorman
2012-01-06 13:28 ` Greg KH
2012-01-06 14:09 ` Mel Gorman
2012-01-05 22:06 ` Andrew Morton
2012-01-05 22:31 ` Mel Gorman
2012-01-05 23:19 ` Andrew Morton
2012-01-09 17:25 ` Mel Gorman
2012-01-07 16:52 ` Paul E. McKenney
2012-01-07 17:05 ` Paul E. McKenney
2012-01-05 15:54 ` Mel Gorman
2012-01-08 16:01 ` Gilad Ben-Yossef [this message]
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