From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 33092DE440 for ; Thu, 22 May 2008 01:43:06 +1000 (EST) Subject: Re: [patch 2/2] powerpc: optimise smp_wmb From: Benjamin Herrenschmidt To: Nick Piggin In-Reply-To: <20080521153420.GG8897@wotan.suse.de> References: <20080521141056.GC8897@wotan.suse.de> <20080521141231.GD8897@wotan.suse.de> <1211383592.8297.195.camel@pasglop> <20080521153420.GG8897@wotan.suse.de> Content-Type: text/plain Date: Wed, 21 May 2008 11:43:00 -0400 Message-Id: <1211384580.8297.199.camel@pasglop> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, paulus@samba.org Reply-To: benh@kernel.crashing.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2008-05-21 at 17:34 +0200, Nick Piggin wrote: > On Wed, May 21, 2008 at 11:26:32AM -0400, Benjamin Herrenschmidt wrote: > > > > On Wed, 2008-05-21 at 16:12 +0200, Nick Piggin wrote: > > > lwsync is the recommended method of store/store ordering on caching enabled > > > memory. For those subarchs which have lwsync, use it rather than eieio for > > > smp_wmb. > > > > Yuck... existence of lwsync depends on the processor at boot time... > > Not according to the __stringify(LWSYNC) that I just removed. At least, > presumably it is always present on 64 bit processors, and 32 bit ones > will be no worse off as they'll continue just using eieio. No, it doesn't exist on power3, but it degrades into a sync Ben.