From: Vincent Guittot <vincent.guittot@linaro.org>
To: Tejun Heo <tj@kernel.org>
Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de,
linux-kernel@vger.kernel.org, parth@linux.ibm.com,
qais.yousef@arm.com, chris.hyser@oracle.com,
pkondeti@codeaurora.org, Valentin.Schneider@arm.com,
patrick.bellasi@matbug.net, David.Laight@aculab.com,
pjt@google.com, pavel@ucw.cz, dhaval.giani@oracle.com,
qperret@google.com, tim.c.chen@linux.intel.com
Subject: Re: [RFC 6/6] sched/fair: Add sched group latency support
Date: Tue, 22 Mar 2022 17:10:36 +0100 [thread overview]
Message-ID: <CAKfTPtA8g-MJMPRM2R_Bfo9rGSyR3cYAUy_j5UrRM+SAB=Mm7w@mail.gmail.com> (raw)
In-Reply-To: <Yji0twS4N+0b/Rs9@slm.duckdns.org>
Hi Tejun,
On Mon, 21 Mar 2022 at 18:24, Tejun Heo <tj@kernel.org> wrote:
>
> Hello,
>
> On Fri, Mar 11, 2022 at 05:14:06PM +0100, Vincent Guittot wrote:
> > Tasks can set its latency priority which is then used to decide to preempt
> > the current running entity of the cfs but sched group entities still have
> > the default latency priority.
> >
> > Add a latency field in task group to set the latency priority of the group
> > which will be used against other entity in the parent cfs.
>
> One thing that bothers me about this interface is that the configuration
> values aren't well defined. We have the same problems with the nice levels
> but at least have them map to well defined weight values, which likely won't
> change in any foreseeable future. The fact that we have the
> not-too-well-defined nice levels as an interface shouldn't be a reason we
> add another one. Provided that this is something scheduler folks want, it'd
> be really great if the interface can be better thought through. What are the
> numbers actually encoding?
latency_nice is quite similar to nice. The nice latency is used as an
index to get a latency weight in the range [-1024:1024]. latency_nice
is in the range [-20:19] and latency_prio shifts it in the range
[0:40] . This index is then used to get the latency weight similar to
how the nice prio is used to get a weight. That being said, the
latency should probably reflect the latency_weight instead of the
latency_prio in order to be aligned with the weight and weight.nice
fields of cgroups.
As described in patch 5 commit message, the weight is then used to
compute a relative offset to check whether the waking task can preempt
the current running task.
Vincent
>
> Thanks.
>
> --
> tejun
next prev parent reply other threads:[~2022-03-22 16:10 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 16:14 [PATCH 0/6] Add latency_nice priority Vincent Guittot
2022-03-11 16:14 ` [PATCH 1/6] sched: Introduce latency-nice as a per-task attribute Vincent Guittot
2022-03-11 16:14 ` [PATCH 2/6] sched/core: Propagate parent task's latency requirements to the child task Vincent Guittot
2022-03-22 0:22 ` Tim Chen
2022-03-22 14:57 ` Vincent Guittot
2022-03-11 16:14 ` [PATCH 3/6] sched: Allow sched_{get,set}attr to change latency_nice of the task Vincent Guittot
2022-03-22 0:22 ` Tim Chen
2022-03-22 14:55 ` Vincent Guittot
2022-03-28 9:23 ` Dietmar Eggemann
2022-03-28 12:41 ` Vincent Guittot
2022-03-11 16:14 ` [PATCH 4/6] sched/core: Add permission checks for setting the latency_nice value Vincent Guittot
2022-03-11 16:14 ` [RFC 5/6] sched/fair: Take into account latency nice at wakeup Vincent Guittot
2022-03-15 0:53 ` Josh Don
2022-03-15 13:54 ` Vincent Guittot
2022-03-28 9:24 ` Dietmar Eggemann
2022-03-28 12:51 ` Vincent Guittot
2022-05-01 15:58 ` Tao Zhou
2022-05-02 9:54 ` Vincent Guittot
2022-05-02 12:30 ` Vincent Guittot
2022-05-02 15:08 ` Tao Zhou
2022-05-02 15:26 ` Tao Zhou
2022-05-02 15:47 ` Tao Zhou
2022-05-02 16:21 ` Vincent Guittot
2022-05-02 23:09 ` Tao Zhou
2022-05-03 2:30 ` Tao Zhou
2022-05-03 12:40 ` Vincent Guittot
2022-05-04 11:14 ` Chen Yu
2022-05-04 12:39 ` Vincent Guittot
2022-03-11 16:14 ` [RFC 6/6] sched/fair: Add sched group latency support Vincent Guittot
2022-03-15 0:58 ` Josh Don
2022-03-15 17:07 ` Vincent Guittot
2022-03-21 17:24 ` Tejun Heo
2022-03-22 16:10 ` Vincent Guittot [this message]
2022-03-22 16:40 ` Tejun Heo
2022-03-23 15:04 ` Vincent Guittot
2022-03-23 18:20 ` Chris Hyser
2022-03-22 16:41 ` Tim Chen
2022-03-23 15:23 ` Vincent Guittot
2022-03-22 16:39 ` [PATCH 0/6] Add latency_nice priority Qais Yousef
2022-03-23 15:32 ` Vincent Guittot
2022-03-24 17:25 ` Qais Yousef
2022-03-25 13:27 ` Vincent Guittot
2022-03-28 16:27 ` Qais Yousef
2022-03-30 7:30 ` Vincent Guittot
2022-03-28 9:24 ` Dietmar Eggemann
2022-03-28 12:56 ` Vincent Guittot
2022-04-01 12:15 ` Qais Yousef
2022-04-02 8:46 ` Vincent Guittot
2022-04-09 17:08 ` Qais Yousef
2022-04-09 17:28 ` Steven Rostedt
2022-04-09 18:10 ` Qais Yousef
2022-04-11 7:26 ` Vincent Guittot
Reply instructions:
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:
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='CAKfTPtA8g-MJMPRM2R_Bfo9rGSyR3cYAUy_j5UrRM+SAB=Mm7w@mail.gmail.com' \
--to=vincent.guittot@linaro.org \
--cc=David.Laight@aculab.com \
--cc=Valentin.Schneider@arm.com \
--cc=bsegall@google.com \
--cc=chris.hyser@oracle.com \
--cc=dhaval.giani@oracle.com \
--cc=dietmar.eggemann@arm.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mgorman@suse.de \
--cc=mingo@redhat.com \
--cc=parth@linux.ibm.com \
--cc=patrick.bellasi@matbug.net \
--cc=pavel@ucw.cz \
--cc=peterz@infradead.org \
--cc=pjt@google.com \
--cc=pkondeti@codeaurora.org \
--cc=qais.yousef@arm.com \
--cc=qperret@google.com \
--cc=rostedt@goodmis.org \
--cc=tim.c.chen@linux.intel.com \
--cc=tj@kernel.org \
/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
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).