From: Gilad Ben-Yossef <gilad@benyossef.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Frederic Weisbecker <fweisbec@gmail.com>,
Christoph Lameter <cl@linux.com>,
Chris Metcalf <cmetcalf@tilera.com>,
linux-mm@kvack.org, Pekka Enberg <penberg@kernel.org>,
Matt Mackall <mpm@selenic.com>, Rik van Riel <riel@redhat.com>,
Andi Kleen <andi@firstfloor.org>,
Sasha Levin <levinsasha928@gmail.com>
Subject: Re: [PATCH v4 2/5] arm: Move arm over to generic on_each_cpu_mask
Date: Wed, 23 Nov 2011 08:47:40 +0200 [thread overview]
Message-ID: <CAOtvUMcus07UY1keOor2=k=iDocKA0GoqYeOQ5r5p6vQ7efwCA@mail.gmail.com> (raw)
In-Reply-To: <20111122210018.GF9581@n2100.arm.linux.org.uk>
Hi,
On Tue, Nov 22, 2011 at 11:00 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Tue, Nov 22, 2011 at 01:08:45PM +0200, Gilad Ben-Yossef wrote:
>> -static void on_each_cpu_mask(void (*func)(void *), void *info, int wait,
>> - const struct cpumask *mask)
>> -{
>> - preempt_disable();
>> -
>> - smp_call_function_many(mask, func, info, wait);
>> - if (cpumask_test_cpu(smp_processor_id(), mask))
>> - func(info);
>> -
>> - preempt_enable();
>> -}
>
> What hasn't been said in the descriptions (I couldn't find it) is that
> there's a semantic change between the new generic version and this version -
> that is, we run the function with IRQs disabled on the local CPU, whereas
> the version above runs it with IRQs potentially enabled.
>
> Luckily, for TLB flushing this is probably not a problem, but it's
> something that should've been pointed out in the patch description.
Thank you for the review!
You are very right that I should have mentioned it in the description.
My apologies for missing that bit.
My reasoning for why the change is OK is that the function passed is
ready to run with interrupt disabled because this is how it will be
called on all the other CPUs through the IPI handler so it is safe.
This is also how the generic on_each_cpu() handles it.
Have I missed something? if not will you like me to update the patch
description and re-send?
Thanks,
Gilad
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Gilad Ben-Yossef
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next prev parent reply other threads:[~2011-11-23 6:47 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-22 11:08 [PATCH v4 0/5] Reduce cross CPU IPI interference Gilad Ben-Yossef
2011-11-22 11:08 ` [PATCH v4 1/5] smp: Introduce a generic on_each_cpu_mask function Gilad Ben-Yossef
2011-11-22 11:08 ` [PATCH v4 2/5] arm: Move arm over to generic on_each_cpu_mask Gilad Ben-Yossef
2011-11-22 21:00 ` Russell King - ARM Linux
2011-11-23 6:47 ` Gilad Ben-Yossef [this message]
2011-11-22 11:08 ` [PATCH v4 3/5] tile: Move tile to use " Gilad Ben-Yossef
2011-11-22 11:08 ` [PATCH v4 4/5] slub: Only IPI CPUs that have per cpu obj to flush Gilad Ben-Yossef
2011-11-23 6:23 ` Pekka Enberg
2011-11-23 6:57 ` Pekka Enberg
2011-11-23 7:52 ` Gilad Ben-Yossef
2012-01-01 12:41 ` Avi Kivity
2012-01-01 16:12 ` Gilad Ben-Yossef
2012-01-01 16:50 ` Avi Kivity
2012-01-02 11:59 ` Gilad Ben-Yossef
2012-01-02 13:30 ` Avi Kivity
2012-01-08 16:13 ` Gilad Ben-Yossef
2012-01-08 16:15 ` Avi Kivity
2011-11-22 11:08 ` [PATCH v4 5/5] mm: Only IPI CPUs to drain local pages if they exist Gilad Ben-Yossef
2011-11-23 7:45 ` Pekka Enberg
2011-12-23 10:28 ` Mel Gorman
2011-12-25 9:39 ` Gilad Ben-Yossef
2011-12-30 15:04 ` Mel Gorman
2011-12-30 15:25 ` Chris Metcalf
2011-12-30 16:08 ` Mel Gorman
2011-12-30 20:29 ` Gilad Ben-Yossef
2012-01-01 8:03 ` Gilad Ben-Yossef
2011-12-30 20:16 ` Gilad Ben-Yossef
2011-11-23 1:36 ` [PATCH v4 0/5] Reduce cross CPU IPI interference Chris Metcalf
2011-11-23 6:52 ` Gilad Ben-Yossef
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