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From: Steven Rostedt <rostedt@goodmis.org>
To: Qais Yousef <qais.yousef@arm.com>
Cc: 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>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] sched: rt: Make RT capacity aware
Date: Mon, 25 Nov 2019 16:36:50 -0500	[thread overview]
Message-ID: <20191125163650.6a624fee@gandalf.local.home> (raw)
In-Reply-To: <20191009104611.15363-1-qais.yousef@arm.com>

Sorry for the very late response...

On Wed,  9 Oct 2019 11:46:11 +0100
Qais Yousef <qais.yousef@arm.com> wrote:

> ATM the uclamp value are only used for frequency selection; but on
> heterogeneous systems this is not enough and we need to ensure that the
> capacity of the CPU is >= uclamp_min. Which is what implemented here.

Is it possible that the capacity can be fixed, where the process can
just have a cpu mask of CPUs that has the capacity for it?

Not that this will affect this patch now, but just something for the
future.

> 
> 	capacity_orig_of(cpu) >= rt_task.uclamp_min
> 
> Note that by default uclamp.min is 1024, which means that RT tasks will
> always be biased towards the big CPUs, which make for a better more
> predictable behavior for the default case.
> 
> Must stress that the bias acts as a hint rather than a definite
> placement strategy. For example, if all big cores are busy executing
> other RT tasks we can't guarantee that a new RT task will be placed
> there.
> 
> On non-heterogeneous systems the original behavior of RT should be
> retained. Similarly if uclamp is not selected in the config.
> 
> Signed-off-by: Qais Yousef <qais.yousef@arm.com>

Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

  parent reply	other threads:[~2019-11-25 21:38 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-09 10:46 [PATCH v2] sched: rt: Make RT capacity aware Qais Yousef
2019-10-23 12:34 ` Qais Yousef
2019-10-28 14:37 ` Peter Zijlstra
2019-10-28 18:01   ` Steven Rostedt
2019-10-28 20:50     ` Peter Zijlstra
2019-12-20 16:01       ` Qais Yousef
2019-12-20 17:18         ` Peter Zijlstra
2019-12-20 17:36           ` Qais Yousef
2019-11-07  9:15     ` Qais Yousef
2019-11-18 15:43     ` Qais Yousef
2019-11-18 15:53       ` Steven Rostedt
2019-11-18 16:12         ` Qais Yousef
2019-10-29  8:13 ` Vincent Guittot
2019-10-29 11:02   ` Qais Yousef
2019-10-29 11:17     ` Vincent Guittot
2019-10-29 11:48       ` Qais Yousef
2019-10-29 12:20         ` Vincent Guittot
2019-10-29 12:46           ` Qais Yousef
2019-10-29 12:54             ` Vincent Guittot
2019-10-29 13:02               ` Peter Zijlstra
2019-10-29 20:36               ` Patrick Bellasi
2019-10-30  8:04                 ` Vincent Guittot
2019-10-30  9:26                   ` Qais Yousef
2019-10-30 12:11                   ` Quentin Perret
2019-10-30 11:57 ` Dietmar Eggemann
2019-10-30 17:43   ` Qais Yousef
2019-11-28 13:59     ` Dietmar Eggemann
2019-11-25 21:36 ` Steven Rostedt [this message]
2019-11-26  9:39   ` Qais Yousef
2019-12-25 10:38 ` [tip: sched/core] sched/rt: Make RT capacity-aware tip-bot2 for Qais Yousef
2020-01-31 10:06 ` [PATCH v2] sched: rt: Make RT capacity aware Pavan Kondeti
2020-01-31 15:34   ` Qais Yousef
     [not found]     ` <CAEU1=PnYryM26F-tNAT0JVUoFcygRgE374JiBeJPQeTEoZpANg@mail.gmail.com>
2020-02-03  5:32       ` Pavan Kondeti
2020-02-03 14:57         ` Qais Yousef
2020-02-03 14:27       ` Qais Yousef
2020-02-03 16:14         ` Steven Rostedt
2020-02-03 17:15           ` Valentin Schneider
2020-02-03 17:17           ` Qais Yousef
2020-02-03 18:12             ` Steven Rostedt
2020-02-03 19:03               ` Qais Yousef
2020-02-04 17:23                 ` Dietmar Eggemann
2020-02-05 14:48                   ` Qais Yousef

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