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Subject: Re: config PROC_CHILDREN
To: Jean Delvare <jdelvare@suse.de>
References: <20150703093918.75b98eb7@endymion.delvare>
 <55965195.6010602@endocode.com> <20150704190728.6a1b8a5a@endymion.delvare>
Cc: LKML <linux-kernel@vger.kernel.org>, Djalal Harouni <djalal@endocode.com>,
        Alban Crequy <alban@endocode.com>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        Andrew Morton <akpm@linux-foundation.org>
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On 07/04/2015 07:07 PM, Jean Delvare wrote:
> Hi Iago,
> 
> Please don't top-post.
> 
> On Fri, 3 Jul 2015 11:10:45 +0200, Iago López Galeiras wrote:
>> Hi Jean,
>>
>> The purpose of this option is enabling /proc/<pid>/task/<tid>/children without
>> having to enable CHECKPOINT_RESTORE, which is hidden behind EXPERT.
>>
>> Regarding its lack of help, documentation is in already in place[1] but perhaps
>> that's not clear for the user because as you say the Kconfig help text is missing.
>>
>> I suggest adding something like:
>>
>>     Provides a fast way to retrieve first level children pids of a task. See
>>     <file:Documentation/filesystems/proc.txt> for more information.
>>
>> Do you think that's enough?
> 
> That's a start, the reference to Documentation/filesystems/proc.txt is
> good but I think we can do better. You need to help the user make the
> decision. Why should he/she say Y or N? The user should NOT have to look
> at an external documentation file if the answer is N. I would suggest
> the following:
> 
> Say Y if running any user-space software which takes benefit from this
> interface. For example, rkt is such a piece of software.

That makes it more clear for the user. Thanks!

> That being said, I am curious... Is this interface so expensive that it
> really deserves a separate option, instead of always enabling it? This
> seems to be a fairly generic feature that a lot of scripts and tools
> could benefit from (starting with pstree I suppose.)

I don't think I have enough information to answer that question. I'll CC Cyrill
Gorcunov and Andrew Morton.

-- 

Iago López Galeiras
Software developer @ Endocode AG
iago@endocode.com