From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Andrea Righi <righi.andrea@gmail.com>
Cc: balbir@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
kosaki.motohiro@jp.fujitsu.com, containers@lists.osdl.org,
menage@google.com, xemul@openvz.org
Subject: Re: [RFC PATCH 5/5] refresh VM committed space after a task migration
Date: Tue, 10 Jun 2008 10:41:28 -0700 [thread overview]
Message-ID: <1213119688.13882.13.camel@nimitz> (raw)
In-Reply-To: <1213054383-18137-6-git-send-email-righi.andrea@gmail.com>
On Tue, 2008-06-10 at 01:33 +0200, Andrea Righi wrote:
> + preempt_disable();
> + committed = atomic_long_read(&p->vm_committed_space);
> + atomic_long_sub(committed, &old_mem->vmacct.vm_committed_space);
> + atomic_long_add(committed, &mem->vmacct.vm_committed_space);
> + preempt_enable();
> out:
> mmput(mm);
> }
Why bother with the preempt stuff here? What does the actually protect
against? I assume that you're trying to keep other tasks that might run
on this CPU from seeing weird, inconsistent numbers in here. Is there
some other looks that keeps *other* cpus from seeing this?
In any case, I think it needs a big, fat comment.
-- Dave
next prev parent reply other threads:[~2008-06-10 17:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-09 23:33 [RFC PATCH 5/5] refresh VM committed space after a task migration Andrea Righi
2008-06-10 17:41 ` Dave Hansen [this message]
2008-06-11 10:37 ` Andrea Righi
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