linux-kernel - Re: [PATCH 2.6.20-rc4 1/4] futex priority based wakeup

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Message-ID: <45A4D5FC.7060808@bull.net>
Date:	Wed, 10 Jan 2007 13:03:08 +0100
From:	Pierre Peiffer <pierre.peiffer@...l.net>
To:	unlisted-recipients:; (no To-header on input)
Cc:	Ulrich Drepper <drepper@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Dinakar Guniguntala <dino@...ibm.com>,
	Jean-Pierre Dion <jean-pierre.dion@...l.net>,
	Ingo Molnar <mingo@...e.hu>, Jakub Jelinek <jakub@...hat.com>,
	Darren Hart <dvhltc@...ibm.com>,
	Sébastien Dugué <sebastien.dugue@...l.net>
Subject: Re: [PATCH 2.6.20-rc4 1/4] futex priority based wakeup

Pierre Peiffer a écrit :
> Ulrich Drepper a écrit :
>>
>> I have never seen performance numbers for this.  If it is punishing
>> existing code in a measurable way I think it's not anacceptable default
>> behavior.

> May be, supposing it makes sense to respect the priority order only for 
> real-time pthreads, I can register all SCHED_OTHER threads to the same 
> MAX_RT_PRIO priotity ?

Moreover, the performance must be considered, sure, but after all, "man 
pthread_cond_broadcast" says:
<<
        If more than one  thread  is  blocked  on  a  condition  variable,  the
        scheduling  policy  shall  determine  the  order  in  which threads are
        unblocked.
 >>

... this is not true today ...
(of course, "shall" does not mean "mandatory", I know ;-) )

-- 
Pierre
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