From: Hari Bathini <hbathini@linux.vnet.ibm.com>
To: Krister Johansen <kjlx@templeofstupid.com>
Cc: ast@fb.com, peterz@infradead.org,
lkml <linux-kernel@vger.kernel.org>,
acme@kernel.org, alexander.shishkin@linux.intel.com,
mingo@redhat.com, daniel@iogearbox.net, rostedt@goodmis.org,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
ebiederm@xmission.com, sargun@sargun.me,
Aravinda Prasad <aravinda@linux.vnet.ibm.com>,
brendan.d.gregg@gmail.com
Subject: Re: [PATCH v4 0/3] perf: add support for analyzing events for containers
Date: Wed, 4 Jan 2017 17:15:02 +0530 [thread overview]
Message-ID: <1d75e250-62dd-6d5b-2644-a79d208b2875@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170104090459.GB3009@templeofstupid.com>
On Wednesday 04 January 2017 02:34 PM, Krister Johansen wrote:
> On Tue, Jan 03, 2017 at 04:57:54PM +0530, Hari Bathini wrote:
>> On Thursday 29 December 2016 07:11 AM, Krister Johansen wrote:
>>> On Fri, Dec 16, 2016 at 12:06:55AM +0530, Hari Bathini wrote:
>>>> This patch-set overcomes this limitation by using cgroup identifier as
>>>> container unique identifier. A new PERF_RECORD_NAMESPACES event that
>>>> records namespaces related info is introduced, from which the cgroup
>>>> namespace's device & inode numbers are used as cgroup identifier. This
>>>> is based on the assumption that each container is created with it's own
>>>> cgroup namespace allowing assessment/analysis of multiple containers
>>>> using cgroup identifier.
>>> Why choose cgroups when the kernel dispenses namespace-unique
>>> identifiers. Cgroup membership can be arbitrary. Moreover, cgroup and
>> Agreed. But doesn't that hold for any other namespace or a combination
>> of namespaces as well?
> I guess that's part of my concern. There is no container-unique
> identifier on the system, since the notion of containers is a construct
> of higer-level software. You're depending on the fact that some popular
> container software packages put their processes in separate cgroups.
> Some of the stranger problems I've debugged with containers involve
> abuses of nsenter(1) and shared subtrees. In cases like that, if you
> filter by cgroup you may miss other interfering processes that are in
> one or more of the namespaces associated with the container, but not its
> cgroup. It's possible I misunderstood. Is the cgroup id being used to
> filter events, or just for display purposes?
All namespaces info for all threads is captured in perf.data with
PERF_RECORD_NAMESPACES events, which can be used
for post processing. We used cgroup namespace's id in
patch 3/3 for reporting, which can be improved later..
Thanks
Hari
next prev parent reply other threads:[~2017-01-04 11:46 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-15 18:36 [PATCH v4 0/3] perf: add support for analyzing events for containers Hari Bathini
2016-12-15 18:37 ` [PATCH v4 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info Hari Bathini
2016-12-15 18:46 ` Peter Zijlstra
2016-12-16 6:27 ` Hari Bathini
2016-12-16 7:57 ` Peter Zijlstra
2016-12-16 18:21 ` Hari Bathini
2016-12-16 20:05 ` Peter Zijlstra
2016-12-21 13:09 ` Hari Bathini
2016-12-21 13:24 ` Peter Zijlstra
2016-12-21 15:56 ` Hari Bathini
2016-12-22 7:21 ` Eric W. Biederman
2016-12-22 7:53 ` Peter Zijlstra
2016-12-22 10:19 ` Eric W. Biederman
2016-12-22 13:24 ` Peter Zijlstra
2016-12-22 18:20 ` Eric W. Biederman
2016-12-15 18:37 ` [PATCH v4 2/3] perf tool: " Hari Bathini
2016-12-17 17:40 ` Jiri Olsa
2016-12-21 13:18 ` Hari Bathini
2016-12-15 18:37 ` [PATCH v4 3/3] perf tool: add cgroup identifier entry in perf report Hari Bathini
2016-12-29 1:41 ` [PATCH v4 0/3] perf: add support for analyzing events for containers Krister Johansen
2017-01-03 11:27 ` Hari Bathini
2017-01-04 9:04 ` Krister Johansen
2017-01-04 11:45 ` Hari Bathini [this message]
2017-01-11 11:16 ` Aravinda Prasad
2017-01-11 14:45 ` Eric W. Biederman
2016-12-16 12:14 Alban Crequy
2016-12-16 18:26 ` Hari Bathini
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