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Date: Thu, 19 Apr 2012 07:34:15 +0400
From: Alexander Nikiforov <a.nikiforov@samsung.com>
Subject: Re: [RFD] Merge task counter into memcg
In-reply-to: <20120417152350.GC32402@google.com>
To: Tejun Heo <tj@kernel.org>
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On 04/17/2012 07:23 PM, Tejun Heo wrote:
> Hello,
>
> On Tue, Apr 17, 2012 at 10:45:05AM +0400, Alexander Nikiforov wrote:
>> between them. Now we have only 1 way to get notification about tasks
>> file - inotify(), but this approach works only if you work from
>> userspace with file (e.g. create struct file, for example with echo
>> $$ /sys/abc/tasks), but when something happens from kernel side
>> (do_fork()/do_exit) we cannot get any event about group of the
>> process (we can scan tasks file and count number of PID, or work
>> with
>> waitpid(), but IMHO this is ugly solutions)
> Wouldn't simply generating FS_MODIFY event on the tasks file do the
> trick?
>
> Thanks.
>
Maybe it will, but in my mind it should be with event. I thought about 
inotify before my RFD mail. Here we have file update, so FS_MODIFY very 
natural.
But on the other hand - we have event in memcg, so conventional approach 
is event.

If this functionality is acceptable in cgroup and FS_MODIFY better, 
we'll make new patch with this approach.

-- 
Best regards,
      Alex Nikiforov,
      Mobile SW, Advanced Software Group,
      Moscow R&D center, Samsung Electronics