From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Paul Menage <menage@google.com>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cpuacct: add a branch prediction
Date: Thu, 26 Feb 2009 17:40:33 +0900 [thread overview]
Message-ID: <20090226174033.094e4834.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <49A65455.4030204@cn.fujitsu.com>
On Thu, 26 Feb 2009 16:35:33 +0800
Li Zefan <lizf@cn.fujitsu.com> wrote:
> ca is not checked before hierarchy support, and it's a side-effect.
>
> Before cpuacct is initialized, css == task->cgroups->subsys[cpuacct_subsys] == NULL,
> but ca = task_ca(tsk) is not necessarily NULL, unless struct cgroup_subsys_state is the
> first member of struct cpuacct.
>
> And the above code actually should be:
>
> do {
> ...
> } while (ca->parent);
>
I'll send no more objections to this patch itself.
But IMHO, this loop is tooo bad, I think. The hierarchy information should be gathered by
read-side and the total code should be
void charge_statistics(tsk, cputime)
{
ca = task_ca(tsk)
/* ca can be null while init */
if (likely(ca)) {
u64 *cpuusage = percpu_ptr(ca->cpuusage, task_cpu(tsk))
*cpuusage += cputime
}
}
(Need changes to read-side and create/destroy of cpuacct cgroups.)
Thanks,
-Kame
next prev parent reply other threads:[~2009-02-26 8:42 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-26 7:40 [PATCH] cpuacct: add a branch prediction Li Zefan
2009-02-26 8:07 ` KAMEZAWA Hiroyuki
2009-02-26 8:17 ` Li Zefan
2009-02-26 8:22 ` KAMEZAWA Hiroyuki
2009-02-26 8:35 ` Li Zefan
2009-02-26 8:40 ` KAMEZAWA Hiroyuki [this message]
2009-02-26 10:10 ` Bharata B Rao
2009-02-26 10:28 ` KAMEZAWA Hiroyuki
2009-02-26 10:44 ` Peter Zijlstra
2009-02-26 10:55 ` KAMEZAWA Hiroyuki
2009-02-26 11:22 ` Peter Zijlstra
2009-02-26 11:17 ` KAMEZAWA Hiroyuki
2009-02-26 11:28 ` Peter Zijlstra
2009-02-26 12:06 ` KAMEZAWA Hiroyuki
2009-02-26 12:20 ` Peter Zijlstra
2009-02-26 12:26 ` Ingo Molnar
2009-02-26 12:40 ` Arnd Bergmann
2009-02-27 4:25 ` Paul Mackerras
2009-02-26 16:45 ` Paul E. McKenney
2009-02-27 0:58 ` KAMEZAWA Hiroyuki
2009-02-27 1:29 ` Paul E. McKenney
2009-02-27 3:22 ` [RFC][PATCH] remove rq->lock from cpuacct cgroup (Was " KAMEZAWA Hiroyuki
2009-03-02 14:56 ` Peter Zijlstra
2009-03-02 23:42 ` KAMEZAWA Hiroyuki
2009-03-03 7:51 ` Peter Zijlstra
2009-03-03 9:04 ` KAMEZAWA Hiroyuki
2009-03-03 9:40 ` Peter Zijlstra
2009-03-03 10:42 ` KAMEZAWA Hiroyuki
2009-03-03 10:44 ` KAMEZAWA Hiroyuki
2009-03-03 11:54 ` Peter Zijlstra
2009-03-04 6:32 ` [PATCH] remove rq->lock from cpuacct cgroup v2 KAMEZAWA Hiroyuki
2009-03-04 7:54 ` Bharata B Rao
2009-03-04 8:20 ` KAMEZAWA Hiroyuki
2009-03-04 8:46 ` KAMEZAWA Hiroyuki
2009-03-04 10:35 ` Bharata B Rao
2009-03-04 12:11 ` Bharata B Rao
2009-03-04 14:17 ` KAMEZAWA Hiroyuki
2009-02-26 8:37 ` [PATCH] cpuacct: add a branch prediction Balbir Singh
2009-02-26 8:41 ` Li Zefan
2009-02-26 10:40 ` Balbir Singh
2009-02-26 10:43 ` Peter Zijlstra
2009-02-26 8:43 ` KAMEZAWA Hiroyuki
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