linux-kernel - RE: Bug 71331 - mlock yields processor to lower priority process

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Date:	Thu, 27 Mar 2014 06:35:35 +0100
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	jimmie.davis@...com.com
Cc:	luto@...capital.net, oneukum@...e.de, artem_fetishev@...m.com,
	peterz@...radead.org, kosaki.motohiro@...fujitsu.com,
	linux-kernel@...r.kernel.org
Subject: RE: Bug 71331 - mlock yields processor to lower priority process

On Thu, 2014-03-27 at 04:20 +0000, jimmie.davis@...com.com wrote: 


> The example code submitted into bugzilla (chase back on the thread a
> bit, there is a reference) shows the problem.
> 
> Two threads, TaskA (high priority) and TaskB (low priority).  Assigned
> to the same processor, explicitly for the guarantee that only one of
> them can execute at a time.

Your priority based serialization guarantee does not exist.  Tasks can
be and are put to sleep.  When that happens, a lower priority runnable
task will run.  Whether you like that fact or not, it remains a fact.

If you don't want your lower priority task to run, why do you wake it?.

-Mike
> 


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