From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.lixom.net (lixom.net [66.141.50.11]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id C5DA5B7BFA for ; Tue, 16 Feb 2010 17:03:07 +1100 (EST) Date: Tue, 16 Feb 2010 00:07:58 -0600 From: Olof Johansson To: Benjamin Herrenschmidt Subject: Re: [PATCH 6/6] powerpc: Use lwsync for acquire barrier if CPU supports it Message-ID: <20100216060758.GA12891@lixom.net> References: <20100210105728.GA3399@kryten> <20100210110236.GB3399@kryten> <20100210110306.GC3399@kryten> <20100210110406.GD3399@kryten> <20100210110719.GE3399@kryten> <20100210111025.GF3399@kryten> <20100216042238.GB12167@lixom.net> <1266293943.16346.169.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1266293943.16346.169.camel@pasglop> Cc: npiggin@suse.de, linuxppc-dev@ozlabs.org, Anton Blanchard List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Feb 16, 2010 at 03:19:03PM +1100, Benjamin Herrenschmidt wrote: > On Mon, 2010-02-15 at 22:22 -0600, Olof Johansson wrote: > > > > Turns out this one hurts PA6T performance quite a bit, lwsync seems to be > > significantly more expensive there. I see a 25% drop in the microbenchmark > > doing pthread_lock/unlock loops on two cpus. > > > > Taking out the CPU_FTR_LWSYNC will solve it, it's a bit unfortunate since > > the sync->lwsync changes definitely still can, and should, be done. > > So we should use a different feature bit. No biggie. If needed we can > split them more anyways. Yeah, fine with me. -Olof