From: Qais Yousef <qais.yousef@arm.com>
To: Pavan Kondeti <pkondeti@codeaurora.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] sched/rt: allow pulling unfitting task
Date: Mon, 17 Feb 2020 11:20:36 +0000 [thread overview]
Message-ID: <20200217112034.54yoockxvfe3fw6y@e107158-lin.cambridge.arm.com> (raw)
In-Reply-To: <20200217091042.GB28029@codeaurora.org>
On 02/17/20 14:40, Pavan Kondeti wrote:
> Hi Qais,
>
> On Fri, Feb 14, 2020 at 04:39:48PM +0000, Qais Yousef wrote:
> > When implemented RT Capacity Awareness; the logic was done such that if
> > a task was running on a fitting CPU, then it was sticky and we would try
> > our best to keep it there.
> >
> > But as Steve suggested, to adhere to the strict priority rules of RT
> > class; allow pulling an RT task to unfitting CPU to ensure it gets a
> > chance to run ASAP. When doing so, mark the queue as overloaded to give
> > the system a chance to push the task to a better fitting CPU when a
> > chance arises.
> >
> > Suggested-by: Steven Rostedt <rostedt@goodmis.org>
> > Signed-off-by: Qais Yousef <qais.yousef@arm.com>
> > ---
> > kernel/sched/rt.c | 16 +++++++++++++---
> > 1 file changed, 13 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> > index 4043abe45459..0c8bac134d3a 100644
> > --- a/kernel/sched/rt.c
> > +++ b/kernel/sched/rt.c
> > @@ -1646,10 +1646,20 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
> >
> > static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
> > {
> > - if (!task_running(rq, p) &&
> > - cpumask_test_cpu(cpu, p->cpus_ptr) &&
> > - rt_task_fits_capacity(p, cpu))
> > + if (!task_running(rq, p) && cpumask_test_cpu(cpu, p->cpus_ptr)) {
> > +
> > + /*
> > + * If the CPU doesn't fit the task, allow pulling but mark the
> > + * rq as overloaded so that we can push it again to a more
> > + * suitable CPU ASAP.
> > + */
> > + if (!rt_task_fits_capacity(p, cpu)) {
> > + rt_set_overload(rq);
> > + rq->rt.overloaded = 1;
> > + }
> > +
>
> Here rq is source rq from which the task is being pulled. I can't understand
> how marking overload condition on source_rq help. Because overload condition
> gets cleared in the task dequeue path. i.e dec_rt_tasks->dec_rt_migration->
> update_rt_migration().
Err yes indeed I rushed this patch. Let me try again.
Thanks
--
Qais Yousef
next prev parent reply other threads:[~2020-02-17 11:20 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 16:39 [PATCH 0/3] RT Capacity Awareness Improvements Qais Yousef
2020-02-14 16:39 ` [PATCH 1/3] sched/rt: cpupri_find: implement fallback mechanism for !fit case Qais Yousef
2020-02-17 17:07 ` Valentin Schneider
2020-02-17 23:34 ` Qais Yousef
2020-02-18 10:01 ` Valentin Schneider
2020-02-17 19:09 ` Dietmar Eggemann
2020-02-17 23:45 ` Qais Yousef
2020-02-18 9:53 ` Dietmar Eggemann
2020-02-18 17:28 ` Qais Yousef
2020-02-18 16:46 ` Steven Rostedt
2020-02-18 17:27 ` Qais Yousef
2020-02-18 18:03 ` Steven Rostedt
2020-02-18 18:52 ` Qais Yousef
2020-02-14 16:39 ` [PATCH 2/3] sched/rt: allow pulling unfitting task Qais Yousef
2020-02-17 9:10 ` Pavan Kondeti
2020-02-17 11:20 ` Qais Yousef [this message]
2020-02-19 13:43 ` Qais Yousef
2020-02-21 8:07 ` Pavan Kondeti
2020-02-21 11:08 ` Qais Yousef
2020-02-14 16:39 ` [PATCH 3/3] sched/rt: fix pushing unfit tasks to a better CPU Qais Yousef
2020-02-17 9:23 ` Pavan Kondeti
2020-02-17 13:53 ` Qais Yousef
2020-02-18 4:16 ` Pavan Kondeti
2020-02-18 17:47 ` Qais Yousef
2020-02-19 2:46 ` Pavan Kondeti
2020-02-19 10:46 ` Qais Yousef
2020-02-19 14:02 ` Qais Yousef
2020-02-21 8:15 ` Pavan Kondeti
2020-02-21 11:12 ` Qais Yousef
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=20200217112034.54yoockxvfe3fw6y@e107158-lin.cambridge.arm.com \
--to=qais.yousef@arm.com \
--cc=bsegall@google.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=peterz@infradead.org \
--cc=pkondeti@codeaurora.org \
--cc=rostedt@goodmis.org \
--cc=vincent.guittot@linaro.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).