From: Gilad Ben-Yossef <gilad@benyossef.com>
To: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@gentwo.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Frederic Weisbecker <fweisbec@gmail.com>,
Russell King <linux@arm.linux.org.uk>,
linux-mm@kvack.org, Matt Mackall <mpm@selenic.com>,
Sasha Levin <levinsasha928@gmail.com>
Subject: Re: [PATCH v2 6/6] slub: only preallocate cpus_with_slabs if offstack
Date: Sun, 13 Nov 2011 10:39:39 +0200 [thread overview]
Message-ID: <CAOtvUMfcus0Gx3z9XA9EEU-QQuAi4aMp7+_cNEVZzsDmzxLavQ@mail.gmail.com> (raw)
In-Reply-To: <1320606618.1428.76.camel@jaguar>
On Sun, Nov 6, 2011 at 9:10 PM, Pekka Enberg <penberg@kernel.org> wrote:
> On Fri, 28 Oct 2011, Gilad Ben-Yossef wrote:
>> > I think if it is up to me, I recommend going the simpler route that
>> > does the allocation in flush_all using GFP_ATOMIC for
>> > CPUMASK_OFFSTACK=y and sends an IPI to all CPUs if it fails, because
>> > it is simpler code and in the end I believe it is also correct.
>
> On Wed, 2011-11-02 at 03:52 -0500, Christoph Lameter wrote:
>> I support that. Pekka?
>
> Sure. I'm OK with that. Someone needs to run some tests to make sure
> it's working with low memory conditions when GFP_ATOMIC allocations
> fail, though.
I've just used the fault injection framework (which is really cool by
the way) to inject an
allocation failure for every cpumask alloc in slub.c flush_all in
CONFIG_CPUMASK_OFFSTACK=y kernel and then forced each kmem cache
to flush by reading sys/kernel/slab/*/alloc_calls and everything seems to be
in order. dmesg log shows the fault injection failing the allocation,
I get an extra debug
trace from the cpumask allocation code and the system keeps chugging along.
While at it I did a similar thing for the drain_all_pages of
mm/page_alloc.c (running
a new version of the code from the previous patch) and forced the
drain to be called
by running ./hackbench 1000. Here again I saw log reports of the code
path being
called (from the fault injection framework), allocation failed and
save for the debug
trace the system continued to work fine (the OOm killer has killed by
shell, but that
is to be expected).
Both of the above with the latest spin of the patch I'll send out soon
after some more tests,
so it looks good.
Thanks!
Gilad
--
Gilad Ben-Yossef
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gilad@benyossef.com
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"Unfortunately, cache misses are an equal opportunity pain provider."
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next prev parent reply other threads:[~2011-11-13 8:39 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-23 15:56 [PATCH v2 0/6] Reduce cross CPU IPI interference Gilad Ben-Yossef
2011-10-23 15:56 ` [PATCH v2 1/6] smp: Introduce a generic on_each_cpu_mask function Gilad Ben-Yossef
2011-10-23 15:56 ` [PATCH v2 2/6] arm: Move arm over to generic on_each_cpu_mask Gilad Ben-Yossef
2011-10-23 15:56 ` [PATCH v2 3/6] tile: Move tile to use " Gilad Ben-Yossef
2011-10-23 15:56 ` [PATCH v2 4/6] mm: Only IPI CPUs to drain local pages if they exist Gilad Ben-Yossef
2011-10-28 16:07 ` Rik van Riel
2011-10-29 15:29 ` Gilad Ben-Yossef
2011-11-02 8:53 ` Christoph Lameter
2011-11-10 8:03 ` Gilad Ben-Yossef
2011-10-23 15:56 ` [PATCH v2 5/6] slub: Only IPI CPUs that have per cpu obj to flush Gilad Ben-Yossef
2011-10-28 4:06 ` Christoph Lameter
2011-10-28 8:50 ` Gilad Ben-Yossef
2011-10-23 15:56 ` [PATCH v2 6/6] slub: only preallocate cpus_with_slabs if offstack Gilad Ben-Yossef
2011-10-28 4:06 ` Christoph Lameter
2011-10-28 9:09 ` Gilad Ben-Yossef
2011-11-02 8:52 ` Christoph Lameter
2011-11-06 19:10 ` Pekka Enberg
2011-11-13 8:39 ` Gilad Ben-Yossef [this message]
-- strict thread matches above, loose matches on Subject: below --
2011-10-23 15:48 [PATCH v2 0/6] Reduce cross CPU IPI interference Gilad Ben-Yossef
2011-10-23 15:48 ` [PATCH v2 6/6] slub: only preallocate cpus_with_slabs if offstack Gilad Ben-Yossef
2011-10-24 5:19 ` Andi Kleen
2011-10-24 6:16 ` Sasha Levin
2011-10-24 8:02 ` Gilad Ben-Yossef
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