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From: Nikita Danilov <nikita@clusterfs.com>
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Date: Sun, 18 Jun 2006 14:58:42 +0400
To: Con Kolivas <kernel@kolivas.org>
Cc: ck list <ck@vds.kolivas.org>,
       Linux Kernel Mailing List <Linux-Kernel@vger.kernel.org>
Subject: Re: [ckpatch][8/29] track_mutexes-1.patch
Newsgroups: gmane.linux.kernel.ck,gmane.linux.kernel
In-Reply-To: <200606181731.14664.kernel@kolivas.org>
References: <200606181731.14664.kernel@kolivas.org>
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Con Kolivas writes:
 > Keep a record of how many mutexes are held by any task. This allows cpu
 > scheduler code to use this information in decision making for tasks that
 > hold contended resources.

Natural extension of this idea is to specify priority bump for every
mutex, with default mutex initializer setting this value to 1.

In fact, this looks like an old UNIX method of specifying priority value
as an argument to the call of sleeping function (sleep, tsleep,
etc.).

 > 
 > Signed-off-by: Con Kolivas <kernel@kolivas.org>
 > 

[...]

 >  	void *journal_info;
 > Index: linux-ck-dev/kernel/fork.c
 > ===================================================================
 > --- linux-ck-dev.orig/kernel/fork.c	2006-06-18 15:20:14.000000000 +1000
 > +++ linux-ck-dev/kernel/fork.c	2006-06-18 15:23:44.000000000 +1000
 > @@ -1022,6 +1022,7 @@ static task_t *copy_process(unsigned lon
 >  	p->io_context = NULL;
 >  	p->io_wait = NULL;
 >  	p->audit_context = NULL;
 > +	p->mutexes_held = 0;

You may also add 

        BUG_ON(p->mutexes_held != 0);

check to do_exit().

Nikita.