Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760549Ab0LOEi7 (ORCPT ); Tue, 14 Dec 2010 23:38:59 -0500 Received: from mail-vw0-f66.google.com ([209.85.212.66]:39406 "EHLO mail-vw0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755930Ab0LOEi5 (ORCPT ); Tue, 14 Dec 2010 23:38:57 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=qmXSCSzMDrVhwUzR58958OAG3a5hV/+AYZ7RU35n6SF/hqhx0YBsML/d4uCx2pnri/ L/l5HBfwXFEolfhZ9FMf2LuzTcsV6Tz2U/iPuevkzDhw/cUAqUvQhRlQbcXVmObOHUbu Mpa5P/p1ik0g/tzH96/+LoGBH1jt6CamKEIiE= Date: Wed, 15 Dec 2010 12:38:40 +0800 From: =?utf-8?Q?Am=C3=A9rico?= Wang To: Nick Piggin Cc: "J. R. Okajima" , Nick Piggin , Linus Torvalds , linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: Big git diff speedup by avoiding x86 "fast string" memcmp Message-ID: <20101215043840.GA7692@cr0.nay.redhat.com> References: <20101209070938.GA3949@amd> <19324.1291990997@jrobl> <20101213014553.GA6522@amd> <9580.1292225351@jrobl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1018 Lines: 26 On Mon, Dec 13, 2010 at 07:25:05PM +1100, Nick Piggin wrote: >On Mon, Dec 13, 2010 at 6:29 PM, J. R. Okajima wrote: >> But is the "rep cmp has quite a long latency" issue generic for all x86 >> architecture, or Westmere system specific? > >I don't believe it is Westmere specific. Intel and AMD have >been improving these instructions in the past few years, so >Westmere is probably as good or better than any. > >That said, rep cmp may not be as heavily optimized as the >set and copy string instructions. > >In short, I think the change should be suitable for all x86 CPUs, >but I would like to hear more opinions or see numbers for other >cores. > How about other arch? If this is only for x86, shouldn't it be protected by CONFIG_X86? Thanks. -- 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/