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From: David Laight <David.Laight@ACULAB.COM>
To: 'Tim Chen' <tim.c.chen@linux.intel.com>,
	Parth Shah <parth@linux.ibm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Patrick Bellasi <patrick.bellasi@arm.com>,
	"subhra mazumdar" <subhra.mazumdar@oracle.com>,
	Valentin Schneider <valentin.schneider@arm.com>
Cc: "mingo@redhat.com" <mingo@redhat.com>,
	"morten.rasmussen@arm.com" <morten.rasmussen@arm.com>,
	"dietmar.eggemann@arm.com" <dietmar.eggemann@arm.com>,
	"pjt@google.com" <pjt@google.com>,
	"vincent.guittot@linaro.org" <vincent.guittot@linaro.org>,
	"quentin.perret@arm.com" <quentin.perret@arm.com>,
	"dhaval.giani@oracle.com" <dhaval.giani@oracle.com>,
	"daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
	"tj@kernel.org" <tj@kernel.org>,
	"rafael.j.wysocki@intel.com" <rafael.j.wysocki@intel.com>,
	"qais.yousef@arm.com" <qais.yousef@arm.com>
Subject: RE: Usecases for the per-task latency-nice attribute
Date: Thu, 19 Sep 2019 09:06:47 +0000	[thread overview]
Message-ID: <9e705d2d22d040f4a170839466b38f5b@AcuMS.aculab.com> (raw)
In-Reply-To: <426c0513-4354-e085-5a5d-8073ab035030@linux.intel.com>

From: Tim Chen
> Sent: 18 September 2019 18:16
...
> Some users are running machine learning batch tasks with AVX512, and have observed
> that these tasks affect the tasks needing a fast response.  They have to
> rely on manual CPU affinity to separate these tasks.  With appropriate
> latency hint on task, the scheduler can be taught to separate them.

Will (or can) the scheduler pre-empt a low priority process that is spinning
in userspace in order to allow a high priority (or low latency) process run
on that cpu?

My suspicion is that the process switch can't happen until (at least) the
next hardware interrupt - and possibly only a timer tick into the scheduler.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  parent reply	other threads:[~2019-09-19  9:06 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-18 12:41 Parth Shah
2019-09-18 14:18 ` Patrick Bellasi
2019-09-18 15:22   ` Vincent Guittot
2019-09-18 15:46     ` Patrick Bellasi
2019-09-18 16:00       ` Vincent Guittot
2019-09-18 15:42   ` Valentin Schneider
2019-09-19 16:41     ` Parth Shah
2019-09-19 18:07       ` Valentin Schneider
2019-09-27 13:53       ` Pavel Machek
2019-09-19  7:01   ` Parth Shah
2019-09-18 17:16 ` Tim Chen
2019-09-19  8:37   ` Parth Shah
2019-09-19 16:27     ` Tim Chen
2019-09-19  9:06   ` David Laight [this message]
2019-09-19 16:30     ` Tim Chen
2019-09-19 14:43 ` Qais Yousef
2019-09-20 10:45   ` Parth Shah

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