From mboxrd@z Thu Jan  1 00:00:00 1970
From: Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH -v5][RFC]: mutex: implement adaptive spinning
Date: Wed, 7 Jan 2009 18:49:45 -0500 (EST)
Message-ID: <alpine.DEB.1.10.0901071848431.23456@gandalf.stny.rr.com>
References: <87r63ljzox.fsf@basil.nowhere.org>  <20090103191706.GA2002@parisc-linux.org> <1231248041.11687.107.camel@twins>  <49636799.1010109@novell.com>  <20090106214229.GD6741@linux.vnet.ibm.com>  <1231278275.11687.111.camel@twins>
 <alpine.LFD.2.00.0901061349520.3057@localhost.localdomain>  <1231279660.11687.121.camel@twins>  <alpine.LFD.2.00.0901061413310.3057@localhost.localdomain>  <1231281801.11687.125.camel@twins>  <1231283778.11687.136.camel@twins>  <1231329783.11687.287.camel@twins>
  <alpine.LFD.2.00.0901070816450.3057@localhost.localdomain>  <1231347442.11687.344.camel@twins>  <alpine.LFD.2.00.0901071016340.3057@localhost.localdomain>  <alpine.DEB.1.10.0901071530490.23456@gandalf.stny.rr.com>  <alpine.LFD.2.00.0901071241360.3057@localhost.localdomain>
  <1231365115.11687.361.camel@twins>  <alpine.LFD.2.00.0901071355350.3057@localhost.localdomain> <1231368870.6686.16.camel@norville.austin.ibm.com> <alpine.LFD.2.00.0901071518570.3057@localhost.localdomain>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	paulmck@linux.vnet.ibm.com, 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 Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-btrfs <linux-btrfs@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nick Piggin <npiggin@suse.de>,
	Peter Morreale <pmorreale@novell.com>,
	Sven Dietrich <SDietrich@novell.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Return-path: <linux-btrfs-owner@vger.kernel.org>
In-Reply-To: <alpine.LFD.2.00.0901071518570.3057@localhost.localdomain>
List-ID: <linux-btrfs.vger.kernel.org>


On Wed, 7 Jan 2009, Linus Torvalds wrote:
> On Wed, 7 Jan 2009, Dave Kleikamp wrote:
> > 
> > Do you need to even do that if CONFIG_DEBUG_PAGEALLOC is unset?
> 
> No.
> 
> > Something like:
> > 
> > #ifdef CONFIG_DEBUG_PAGEALLOC
> >                 /*
> >                  * Need to access the cpu field knowing that
> >                  * DEBUG_PAGEALLOC could have unmapped it if
> >                  * the mutex owner just released it and exited.
> >                  */
> >                 if (probe_kernel_address(&thread->cpu, cpu))
> >                         break;
> > #else
> > 		cpu = thread->cpu;
> > #endif
> 
> yes. That would work fine.

What about memory hotplug as Ingo mentioned?

Should that be:

#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_MEMORY_HOTPLUG)

??

-- Steve