From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1757267AbaE2KlK (ORCPT <rfc822;w@1wt.eu>);
	Thu, 29 May 2014 06:41:10 -0400
Received: from relay.parallels.com ([195.214.232.42]:57534 "EHLO
	relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1757173AbaE2KlI (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 29 May 2014 06:41:08 -0400
Message-ID: <53870EA1.1040302@parallels.com>
Date: Thu, 29 May 2014 14:40:33 +0400
From: Pavel Emelyanov <xemul@parallels.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0
MIME-Version: 1.0
To: "chenhanxiao@cn.fujitsu.com" <chenhanxiao@cn.fujitsu.com>
CC: Vasily Kulikov <segoon@openwall.com>,
        Richard Weinberger <richard.weinberger@gmail.com>,
        "containers@lists.linux-foundation.org" 
	<containers@lists.linux-foundation.org>,
        Serge Hallyn <serge.hallyn@ubuntu.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Oleg Nesterov <oleg@redhat.com>, David Howells <dhowells@redhat.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        "Gotou, Yasunori" <y-goto@jp.fujitsu.com>
Subject: Re: [PATCH v2] /proc/pid/status: show all sets of pid according to
 ns
References: <1401272683-1659-1-git-send-email-chenhanxiao@cn.fujitsu.com> <5385DA19.2060008@parallels.com> <20140528182824.GA5057@cachalot> <53863889.9080509@parallels.com> <20140529055954.GA10354@cachalot> <5386F8EA.8050501@parallels.com> <5871495633F38949900D2BF2DC04883E52A481@G08CNEXMBPEKD02.g08.fujitsu.local>
In-Reply-To: <5871495633F38949900D2BF2DC04883E52A481@G08CNEXMBPEKD02.g08.fujitsu.local>
Content-Type: text/plain; charset="GB2312"
Content-Transfer-Encoding: 7bit
X-Originating-IP: [10.24.36.87]
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 05/29/2014 01:53 PM, chenhanxiao@cn.fujitsu.com wrote:
> 
> 
>> -----Original Message-----
>> From: containers-bounces@lists.linux-foundation.org
>> On 05/29/2014 09:59 AM, Vasily Kulikov wrote:
>>> On Wed, May 28, 2014 at 23:27 +0400, Pavel Emelyanov wrote:
>>>> On 05/28/2014 10:28 PM, Vasily Kulikov wrote:
>>>>> On Wed, May 28, 2014 at 16:44 +0400, Pavel Emelyanov wrote:
>>>>> It will be simplier
>>>>> to parse the file -- if 'ns_ids' file contains some ID then this ID for
>>>>> every ns can be obtained regardless of the specific ID name (SID, PID,
>>>>> PGID, etc.).
>>>>
>>>> True, but given a task PID how to determine which pid namespaces it lives in
>>>> to get the idea of how PIDs map to each other? Maybe we need some explicit
>>>> API for converting (ID, NS1, NS2) into (ID)?
>>>
>>> AFAIU the idea of the patch is to add a new debugging information which
>>> can be trivially obtained via 'cat /proc/...':
>>
>> I agree, but this ability will be very useful by checkpoint-restore project
>> too and I'd really appreciate if the API we have for that would be scalable
>> enough. Per-task proc file works for me, but how about sid-s and pgid-s?
>>
> 
> Yes, a new syscall is very useful, but it should be another task.
> Just for Pids, I think proc file is good enough.

It is, but since we're going to think about more generic API, that would serve
your needs as well, why do we need two APIs?

Thanks,
Pavel