Linux-Fsdevel Archive on lore.kernel.org
 help / color / Atom feed
From: 王贇 <yun.wang@linux.alibaba.com>
To: "Michal Koutný" <mkoutny@suse.com>
Cc: Mel Gorman <mgorman@suse.de>, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Iurii Zaikin <yzaikin@google.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org,
	"Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: Re: [PATCH v2 1/3] sched/numa: advanced per-cgroup numa statistic
Date: Thu, 28 Nov 2019 21:41:37 +0800
Message-ID: <e008fef6-06d2-28d3-f4d3-229f4b181b4f@linux.alibaba.com> (raw)
In-Reply-To: <20191128123924.GD831@blackbody.suse.cz>

On 2019/11/28 下午8:39, Michal Koutný wrote:
> Hello.
> 
> My primary concern is still the measuring of per-NUMA node execution
> time.
> 
> First, I think exposing the aggregated data into the numa_stat file is
> loss of information. The data are collected per-CPU and then summed over
> NUMA nodes -- this could be easily done by the userspace consumer of the
> data, keeping the per-CPU data available.
> 
> Second, comparing with the cpuacct implementation, yours has only jiffy
> granularity (I may have overlooked something or I miss some context,
> then it's a non-concern).

There are used to be a discussion on this, Peter mentioned we no longer
expose raw ticks into userspace and micro seconds could be fine.

Basically we use this to calculate percentages, for which jiffy could be
accurate enough :-)

> 
> IOW, to me it sounds like duplicating cpuacct job and if that is deemed
> useful for cgroup v2, I think it should be done (only once) and at
> proper place (i.e. how cputime is measured in the default hierarchy).

But still, what if folks don't use v2... any good suggestions?

> 
> The previous two are design/theoretical remarks, however, your patch
> misses measuring of other than fair_sched_class policy tasks. Is that
> intentional?

Yes, since they don't have NUMA balancing to do optimization, and
generally they are not that much.

> 
> My last two comments are to locality measurement but are based on no
> experience or specific knowledge.
> 
> The seven percentile groups seem quite arbitrary to me, I find it
> strange that the ratio of cache-line size and u64 leaks and is fixed in
> the generally visible file. Wouldn't such a form be better hidden under
> a _DEBUG config option?

Sorry but I don't get it... at first it was 10 regions, as Peter suggested
we pick 8, but now to insert member 'jiffies' it become 7, the address of
'jiffies' is cache aligned, so we pick u64 * 8 == 64Bytes to make sure the
whole thing could be load in cache once a time, or did I misunderstand
something?

> 
> 
> On Thu, Nov 28, 2019 at 10:09:13AM +0800, 王贇 <yun.wang@linux.alibaba.com> wrote:
>> Consider it as load_1/5/15 which not accurate but tell the trend of system
> I understood your patchset provides cumulative data over time, i.e. if
> a user wants to see an immediate trend, they have to calculate
> differences. Have I overlooked some back-off or regular zeroing?

Yes, here what I try to highlight is the similar usage, but not the way of
monitoring ;-) as the docs tell, we monitoring increments.

Regards,
Michale Wang

> 
> Michal
> 

  reply index

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-13  3:43 [PATCH 0/3] sched/numa: introduce advanced " 王贇
2019-11-13  3:44 ` [PATCH 1/3] sched/numa: advanced per-cgroup " 王贇
2019-11-13  3:45 ` [PATCH 2/3] sched/numa: expose per-task pages-migration-failure 王贇
2019-11-13  3:45 ` [PATCH 3/3] sched/numa: documentation for per-cgroup numa stat 王贇
2019-11-13 15:09   ` Jonathan Corbet
2019-11-14  1:52     ` 王贇
2019-11-13 18:28   ` Iurii Zaikin
2019-11-14  2:22     ` 王贇
2019-11-15  2:29   ` [PATCH v2 " 王贇
2019-11-20  9:45 ` [PATCH 0/3] sched/numa: introduce advanced numa statistic 王贇
2019-11-25  1:35 ` 王贇
2019-11-27  1:48 ` [PATCH v2 " 王贇
2019-11-27  1:49   ` [PATCH v2 1/3] sched/numa: advanced per-cgroup " 王贇
2019-11-27 10:19     ` Mel Gorman
2019-11-28  2:09       ` 王贇
2019-11-28 12:39         ` Michal Koutný
2019-11-28 13:41           ` 王贇 [this message]
2019-11-28 15:58             ` Michal Koutný
2019-11-29  1:52               ` 王贇
2019-11-29  5:19                 ` 王贇
2019-11-29 10:06                   ` Michal Koutný
2019-12-02  2:11                     ` 王贇
2019-11-27  1:50   ` [PATCH v2 2/3] sched/numa: expose per-task pages-migration-failure 王贇
2019-11-27 10:00     ` Mel Gorman
2019-12-02  2:22     ` 王贇
2019-11-27  1:50   ` [PATCH v2 3/3] sched/numa: documentation for per-cgroup numa stat 王贇
2019-11-27  4:58     ` Randy Dunlap
2019-11-27  5:54       ` 王贇
2019-12-03  5:59   ` [PATCH v3 0/2] sched/numa: introduce numa locality 王贇
2019-12-03  6:00     ` [PATCH v3 1/2] sched/numa: introduce per-cgroup NUMA locality info 王贇
2019-12-04  2:33       ` Randy Dunlap
2019-12-04  2:38         ` 王贇
2019-12-03  6:02     ` [PATCH v3 2/2] sched/numa: documentation for per-cgroup numa statistics 王贇
2019-12-03 13:43       ` Jonathan Corbet
2019-12-04  2:27         ` 王贇
2019-12-04  7:58     ` [PATCH v4 0/2] sched/numa: introduce numa locality 王贇
2019-12-04  7:59       ` [PATCH v4 1/2] sched/numa: introduce per-cgroup NUMA locality info 王贇
2019-12-05  3:28         ` Randy Dunlap
2019-12-05  3:29           ` Randy Dunlap
2019-12-05  3:52             ` 王贇
2019-12-04  8:00       ` [PATCH v4 2/2] sched/numa: documentation for per-cgroup numa statistics 王贇
2019-12-05  3:40         ` Randy Dunlap
2019-12-05  6:53       ` [PATCH v5 0/2] sched/numa: introduce numa locality 王贇
2019-12-05  6:53         ` [PATCH v5 1/2] sched/numa: introduce per-cgroup NUMA locality info 王贇
2019-12-05  6:54         ` [PATCH v5 2/2] sched/numa: documentation for per-cgroup numa, statistics 王贇
2019-12-10  2:19         ` [PATCH v5 0/2] sched/numa: introduce numa locality 王贇
2019-12-13  1:43         ` [PATCH v6 " 王贇
2019-12-13  1:47           ` [PATCH v6 1/2] sched/numa: introduce per-cgroup NUMA locality info 王贇
2020-01-03 15:14             ` Michal Koutný
2020-01-04  4:51               ` 王贇
2019-12-13  1:48           ` [PATCH v6 2/2] sched/numa: documentation for per-cgroup numa 王贇
2019-12-27  2:22           ` [PATCH v6 0/2] sched/numa: introduce numa locality 王贇
2020-01-17  2:19           ` 王贇
2020-01-19  6:08           ` [PATCH v7 " 王贇
2020-01-19  6:09             ` [PATCH v7 1/2] sched/numa: introduce per-cgroup NUMA locality info 王贇
2020-01-19  6:09             ` [PATCH v7 2/2] sched/numa: documentation for per-cgroup numa, statistics 王贇
2020-01-21  0:12               ` Randy Dunlap
2020-01-21  1:58                 ` 王贇
2020-01-21  1:56             ` [PATCH v8 0/2] sched/numa: introduce numa locality 王贇
2020-01-21  1:57               ` [PATCH v8 1/2] sched/numa: introduce per-cgroup NUMA locality info 王贇
2020-01-21  1:57               ` [PATCH v8 2/2] sched/numa: documentation for per-cgroup numa, statistics 王贇
2020-01-21  2:08                 ` Randy Dunlap

Reply instructions:

You may reply publically 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:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=e008fef6-06d2-28d3-f4d3-229f4b181b4f@linux.alibaba.com \
    --to=yun.wang@linux.alibaba.com \
    --cc=bsegall@google.com \
    --cc=dietmar.eggemann@arm.com \
    --cc=juri.lelli@redhat.com \
    --cc=keescook@chromium.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mcgrof@kernel.org \
    --cc=mgorman@suse.de \
    --cc=mingo@redhat.com \
    --cc=mkoutny@suse.com \
    --cc=paulmck@linux.ibm.com \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=vincent.guittot@linaro.org \
    --cc=yzaikin@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Fsdevel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-fsdevel/0 linux-fsdevel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-fsdevel linux-fsdevel/ https://lore.kernel.org/linux-fsdevel \
		linux-fsdevel@vger.kernel.org
	public-inbox-index linux-fsdevel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-fsdevel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git