From: Glauber Costa <email@example.com>
To: Paul Turner <firstname.lastname@example.org>
Cc: Tejun Heo <email@example.com>,
Peter Zijlstra <firstname.lastname@example.org>,
<email@example.com>, <firstname.lastname@example.org>, <email@example.com>,
Dhaval Giani <firstname.lastname@example.org>,
Frederic Weisbecker <email@example.com>
Subject: Re: [RFC 0/5] forced comounts for cgroups.
Date: Fri, 7 Sep 2012 02:36:36 +0400 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
On 09/07/2012 01:11 AM, Paul Turner wrote:
> On Thu, Sep 6, 2012 at 1:46 PM, Tejun Heo <email@example.com> wrote:
>> cc'ing Dhaval and Frederic. They were interested in the subject
>> before and Dhaval was pretty vocal about cpuacct having a separate
>> hierarchy (or at least granularity).
> Really? Time just has _not_ borne out this use-case. I'll let Dhaval
> make a case for this but he should expect violent objection.
I strongly advise against physical violence. In case it is really
necessary, please break his legs only.
>> On Wed, Sep 05, 2012 at 12:04:47PM +0200, Peter Zijlstra wrote:
>>>> cpuacct is rather unique tho. I think it's gonna be silly whether the
>>>> hierarchy is unified or not.
>>>> 1. If they always can live on the exact same hierarchy, there's no
>>>> point in having the two separate. Just merge them.
>>>> 2. If they need differing levels of granularity, they either need to
>>>> do it completely separately as they do now or have some form of
>>>> dynamic optimization if absolutely necesary.
>>>> So, I think that choice is rather separate from other issues. If
>>>> cpuacct is gonna be kept, I'd just keep it separate and warn that it
>>>> incurs extra overhead for the current users if for nothing else.
>>>> Otherwise, kill it or merge it into cpu.
>>> Quite, hence my 'proposal' to remove cpuacct.
>>> There was some whining last time Glauber proposed this, but the one
>>> whining never convinced and has gone away from Linux, so lets just do
>>> Lets make cpuacct print a deprecated msg to dmesg for a few releases and
>>> make cpu do all this.
>> I like it. Currently cpuacct is the only problematic one in this
>> regard (cpuset to a much lesser extent) and it would be great to make
>> it go away.
>> Dhaval, Frederic, Paul, if you guys object, please voice your
>>> The co-mounting stuff would have been nice for cpusets as well, knowing
>>> all your tasks are affine to a subset of cpus allows for a few
>>> optimizations (smaller cpumask iterations), but I guess we'll have to do
>>> that dynamically, we'll just have to see how ugly that is.
>> Forced co-mounting sounds rather silly to me. If the two are always
>> gonna be co-mounted, why not just merge them and switch the
>> functionality depending on configuration? I'm fairly sure the code
>> would be simpler that way.
> It would be simpler but the problem is we'd break any userspace that
> was just doing mount cpuacct?
> Further, even if it were mounting both, userspace code still has to be
> changed to read from "cpu.export" instead of "cpuacct.export".
Only if we remove cpuacct. What we can do, and I thought about doing, is
just merging cpuacct functionality into cpu. Then we move cpuacct to
default no. It will be there for userspace if they absolutely want to
> I think a sane path on this front is:
> Don't allow cpuacct and cpu to be co-mounted on separate hierarchies
that is precisely what my patch does, except it is a bit more generic.
> That is:
> mount none /dev/cgroup/cpuacct -t cgroupfs -o cpuacct : still works
> mount none /dev/cgroup/cpu -t cgroupfs -o cpu : still works
> mount none /dev/cgroup/cpux -t cgroupfs -o cpuacct,cpu : still works
> But the combination:
> mount none /dev/cgroup/cpu -t cgroupfs -o cpu : still works
> mount none /dev/cgroup/cpuacct -t cgroupfs -o cpu : EINVAL [or vice versa].
> WARN_ON when mounting cpuacct without cpu, strongly explaining that
> ANY such configuration is deprecated.
> Glauber's patchset goes most of the way towards enabling this.
> In a release or two:
> Make the restriction strict; don't allow individual mounting of
> cpuacct, force it to be mounted ONLY with cpu.
> Glauber's patchset gives us this.
> Mirror the interfaces to cpu, print nasty syslog messages about ANY
> mounts of cpuacct
> Follow that up by eventually removing cpuacct completely
Why don't start with mirroring? It gives more time for people to start
switching to it.
next prev parent reply other threads:[~2012-09-06 22:40 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-04 14:18 [RFC 0/5] forced comounts for cgroups Glauber Costa
2012-09-04 14:18 ` [RFC 1/5] cgroup: allow some comounts to be forced Glauber Costa
2012-09-04 14:18 ` [RFC 2/5] sched: adjust exec_clock to use it as cpu usage metric Glauber Costa
2012-09-04 14:18 ` [RFC 3/5] sched: do not call cpuacct_charge when cpu and cpuacct are comounted Glauber Costa
2012-09-04 14:18 ` [RFC 4/5] cpuacct: do not gather cpuacct statistics when not mounted Glauber Costa
2012-09-04 14:18 ` [RFC 5/5] sched: add cpusets to comounts list Glauber Costa
2012-09-04 21:46 ` [RFC 0/5] forced comounts for cgroups Tejun Heo
2012-09-05 8:03 ` Glauber Costa
2012-09-05 8:14 ` Tejun Heo
2012-09-05 8:17 ` Glauber Costa
2012-09-05 8:29 ` Tejun Heo
2012-09-05 8:35 ` Glauber Costa
2012-09-05 8:47 ` Tejun Heo
2012-09-05 8:55 ` Glauber Costa
2012-09-05 9:07 ` Tejun Heo
2012-09-05 9:06 ` Glauber Costa
2012-09-05 9:14 ` Tejun Heo
2012-09-05 9:06 ` Peter Zijlstra
2012-09-05 9:07 ` Peter Zijlstra
2012-09-05 9:22 ` Tejun Heo
2012-09-05 9:11 ` Tejun Heo
2012-09-05 9:12 ` Glauber Costa
2012-09-05 9:19 ` Tejun Heo
2012-09-05 9:30 ` Glauber Costa
2012-09-05 9:26 ` Peter Zijlstra
2012-09-05 9:31 ` Glauber Costa
2012-09-05 9:45 ` Tejun Heo
2012-09-05 9:48 ` Glauber Costa
2012-09-05 9:56 ` Tejun Heo
2012-09-05 10:20 ` Peter Zijlstra
2012-09-06 20:38 ` Tejun Heo
2012-09-06 22:39 ` Glauber Costa
2012-09-06 22:45 ` Tejun Heo
2012-09-05 9:32 ` Tejun Heo
2012-09-05 10:04 ` Peter Zijlstra
2012-09-06 20:46 ` Tejun Heo
2012-09-06 21:11 ` Paul Turner
2012-09-06 22:36 ` Glauber Costa [this message]
2012-09-08 13:36 ` Dhaval Giani
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).