Subject: Re: [PATCH][RFC]: mutex: adaptive spin
From: Peter Zijlstra <peterz@infradead.org>
To: paulmck@linux.vnet.ibm.com
Cc: Gregory Haskins <ghaskins@novell.com>, Ingo Molnar <mingo@elte.hu>,
       Matthew Wilcox <matthew@wil.cx>, Andi Kleen <andi@firstfloor.org>,
       Chris Mason <chris.mason@oracle.com>,
       Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
       linux-fsdevel <linux-fsdevel@vger.kernel.org>,
       linux-btrfs <linux-btrfs@vger.kernel.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       Steven Rostedt <rostedt@goodmis.org>, Nick Piggin <npiggin@suse.de>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Peter Morreale <pmorreale@novell.com>,
       Sven Dietrich <SDietrich@novell.com>
In-Reply-To: <20090106214229.GD6741@linux.vnet.ibm.com>
References: <87r63ljzox.fsf@basil.nowhere.org>
	 <20090103191706.GA2002@parisc-linux.org> <1231093310.27690.5.camel@twins>
	 <20090104184103.GE2002@parisc-linux.org> <1231242031.11687.97.camel@twins>
	 <20090106121052.GA27232@elte.hu> <4963584A.4090805@novell.com>
	 <20090106131643.GA15228@elte.hu> <1231248041.11687.107.camel@twins>
	 <49636799.1010109@novell.com>  <20090106214229.GD6741@linux.vnet.ibm.com>
Content-Type: text/plain
Content-Transfer-Encoding: 7bit
Date: Tue, 06 Jan 2009 22:44:35 +0100
Message-Id: <1231278275.11687.111.camel@twins>
Mime-Version: 1.0
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 821
Lines: 17

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...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/