From: Tejun Heo <tj@kernel.org>
To: Glauber Costa <glommer@parallels.com>
Cc: cgroups@vger.kernel.org, netdev@vger.kernel.org,
Li Zefan <lizefan@huawei.com>,
kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org,
devel@openvz.org
Subject: Re: [PATCH v3 2/2] decrement static keys on real destroy time
Date: Thu, 26 Apr 2012 15:13:24 -0700 [thread overview]
Message-ID: <20120426221324.GE27486@google.com> (raw)
In-Reply-To: <4F99C50D.6070503@parallels.com>
Hello, Glauber.
On Thu, Apr 26, 2012 at 06:58:37PM -0300, Glauber Costa wrote:
> At first I though that we could get rid of all this complication by
> calling stop machine from the static_branch API. This would all
> magically go away. I actually even tried it.
>
> However, reading the code for other architectures (other than x86),
> I found that they usually rely on the fixed instruction size to just
> patch an instruction atomically and go home happy.
>
> Using stop machine and the like would slow them down considerably.
> Not only slow down the static branch update (which is acceptable),
> but everybody else (which is horrible). It seemed to defeat the
> purpose of static branches a bit.
>
> The other users of static branches seems to be fine coping with the
> fact that in cases with multiple-sites, they will spread in time.
No, what I mean is that why can't you do about the same mutexed
activated inside static_key API function instead of requiring every
user to worry about the function returning asynchronously.
ie. synchronize inside static_key API instead of in the callers.
Thanks.
--
tejun
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next prev parent reply other threads:[~2012-04-26 22:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-26 21:24 [PATCH v3 0/2] fix problem with static_branch() for sock memcg Glauber Costa
2012-04-26 21:24 ` [PATCH v3 1/2] Always free struct memcg through schedule_work() Glauber Costa
2012-04-26 21:24 ` [PATCH v3 2/2] decrement static keys on real destroy time Glauber Costa
2012-04-26 21:39 ` Tejun Heo
2012-04-26 21:58 ` Glauber Costa
2012-04-26 22:13 ` Tejun Heo [this message]
2012-04-26 22:17 ` Glauber Costa
2012-04-26 22:22 ` Tejun Heo
2012-04-26 22:28 ` Glauber Costa
2012-04-26 22:32 ` Tejun Heo
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