linux-kernel - Re: [PATCH][RFC]: mutex: adaptive spin

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Message-ID: <20090106223150.GF6741@linux.vnet.ibm.com>
Date:	Tue, 6 Jan 2009 14:31:50 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Gregory Haskins <ghaskins@...ell.com>, Ingo Molnar <mingo@...e.hu>,
	Matthew Wilcox <matthew@....cx>,
	Andi Kleen <andi@...stfloor.org>,
	Chris Mason <chris.mason@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-btrfs <linux-btrfs@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Steven Rostedt <rostedt@...dmis.org>,
	Nick Piggin <npiggin@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Morreale <pmorreale@...ell.com>,
	Sven Dietrich <SDietrich@...ell.com>
Subject: Re: [PATCH][RFC]: mutex: adaptive spin

On Tue, Jan 06, 2009 at 10:44:35PM +0100, Peter Zijlstra wrote:
> On Tue, 2009-01-06 at 13:42 -0800, Paul E. McKenney wrote:
> > Preemptable RCU needs to be faster.  Got it -- and might have a way
> > to do it by eliminating the irq disabling and cutting way back on the
> > number of operations that must be performed.  It would probably still
> > be necessary to access the task structure.
> > 
> > Or is something other than the raw performance of rcu_read_lock() and
> > rcu_read_unlock() at issue here?
> 
> With Linus' mutex_spin_or_schedule() function the whole - keeping
> owner's task_struct alive issue goes away,.. now if only the thing would
> boot...

Cool!  And I can relate to the "if only the thing would boot" part.  ;-)

							Thanx, Paul
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