From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org, rusty@rustcorp.com.au,
sivanich@sgi.com, heiko.carstens@de.ibm.com,
torvalds@linux-foundation.org, mingo@elte.hu,
peterz@infradead.org, dipankar@in.ibm.com, josh@freedesktop.org,
paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org
Subject: Re: [PATCH 2/4] stop_machine: reimplement using cpuhog
Date: Tue, 09 Mar 2010 08:22:59 +0900 [thread overview]
Message-ID: <4B9586D3.2020109@kernel.org> (raw)
In-Reply-To: <20100308190606.GB9149@redhat.com>
Hello,
On 03/09/2010 04:06 AM, Oleg Nesterov wrote:
> On 03/09, Tejun Heo wrote:
>>
>> int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus)
>> {
>> ...
>> + /* Set the initial state and hog all online cpus. */
>> + set_state(&smdata, STOPMACHINE_PREPARE);
>> + return hog_cpus(cpu_online_mask, stop_cpu, &smdata);
>> }
>
> Could you please confirm this is correct?
>
> I am not sure I understand how the code looks with the patch applied,
> but the lockless set_state() above can confuse another stop_machine()
> in progress?
set_state() now modifies smdata->state and smdata is now local
variable of __stop_machine(). stop_machine instances don't have any
shared resource anymore. Synchronization and resource sharing are all
cpuhog's responsibilities.
Thanks.
--
tejun
next prev parent reply other threads:[~2010-03-08 23:20 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-08 15:53 [PATCHSET] cpuhog: implement and use cpuhog Tejun Heo
2010-03-08 15:53 ` [PATCH 1/4] cpuhog: implement cpuhog Tejun Heo
2010-03-08 19:01 ` Oleg Nesterov
2010-03-08 23:18 ` Tejun Heo
2010-03-08 15:53 ` [PATCH 2/4] stop_machine: reimplement using cpuhog Tejun Heo
2010-03-08 16:32 ` Arjan van de Ven
2010-03-08 23:21 ` Tejun Heo
2010-03-08 17:10 ` Heiko Carstens
2010-03-08 18:27 ` Oleg Nesterov
2010-03-08 19:37 ` Heiko Carstens
2010-03-08 23:39 ` Tejun Heo
2010-03-09 7:09 ` Heiko Carstens
2010-03-09 7:16 ` Tejun Heo
2010-03-08 19:06 ` Oleg Nesterov
2010-03-08 23:22 ` Tejun Heo [this message]
2010-03-08 15:53 ` [PATCH 3/4] scheduler: replace migration_thread with cpuhog Tejun Heo
2010-03-08 15:53 ` [PATCH 4/4] scheduler: kill paranoia check in synchronize_sched_expedited() Tejun Heo
2010-03-10 19:25 ` [PATCHSET] cpuhog: implement and use cpuhog Peter Zijlstra
2010-03-12 3:13 ` Tejun Heo
2010-03-29 6:46 ` Rusty Russell
2010-03-29 9:11 ` Peter Zijlstra
2010-04-02 5:45 ` Tejun Heo
-- strict thread matches above, loose matches on Subject: below --
2010-03-17 8:40 [PATCHSET sched/core] cpuhog: implement and use cpuhog, take#2 Tejun Heo
2010-03-17 8:40 ` [PATCH 2/4] stop_machine: reimplement using cpuhog Tejun Heo
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