From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753675AbZB1Luo (ORCPT ); Sat, 28 Feb 2009 06:50:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750841AbZB1Lug (ORCPT ); Sat, 28 Feb 2009 06:50:36 -0500 Received: from smtp120.mail.mud.yahoo.com ([209.191.84.77]:29066 "HELO smtp120.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750828AbZB1Luf (ORCPT ); Sat, 28 Feb 2009 06:50:35 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:X-Yahoo-Newman-Property:From:To:Subject:Date:User-Agent:Cc:References:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Content-Disposition:Message-Id; b=nMtO30eT6xC80i8RPaEsRzlHufywTKwjq3G5dC2s63MC+koJvOeC+gxyUa1Cf6ZHwLCY6P6OZ92q4xveShS5z2UJ+IBTfi/wiHP4M/YYOOntkv/TBK2bxTUhdk8F0UARlOYorpkH63z23Z7zG2wgRE0slddyDtIKvbwe5BAE0GM= ; X-YMail-OSG: CntEMB0VM1n2djCqyCH_.DEK31GeL3VwL1uPwxcpv2v4_42Ybd.4oBsT52_f6U3G08nhStCoXhZ7xct576uRMnHqTwpGTYjO9MmwrjIL7HhXXUbgXt6EDusHsbb.ShVzYY4Ddam8sPVVz_R7byD7CuoBYxdgHBuF8QHgpsSIRW9HHezMhjnzimStZrJLwFbk0pxDG4JVOjnjaI_7jc5gDmUPKZKypzMFRzc- X-Yahoo-Newman-Property: ymail-3 From: Nick Piggin To: Ingo Molnar Subject: Re: [patch] x86, mm: pass in 'total' to __copy_from_user_*nocache() Date: Sat, 28 Feb 2009 22:49:56 +1100 User-Agent: KMail/1.9.51 (KDE/4.0.4; ; ) Cc: Linus Torvalds , Salman Qazi , davem@davemloft.net, linux-kernel@vger.kernel.org, Thomas Gleixner , "H. Peter Anvin" , Andi Kleen References: <20090224020304.GA4496@google.com> <200902272305.01867.nickpiggin@yahoo.com.au> <20090228082922.GB11425@elte.hu> In-Reply-To: <20090228082922.GB11425@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200902282249.57479.nickpiggin@yahoo.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Saturday 28 February 2009 19:29:22 Ingo Molnar wrote: > * Nick Piggin wrote: > > On Thursday 26 February 2009 03:04:22 Linus Torvalds wrote: > > > And we pretty much know that the only time we will ever really care > > > about the nontemporal case is with big writes - where the "edge > > > effects" essentially become total noise. > > > > I guess so. I wouldn't mind just doing cached stores all the > > time for the reasons you say. > > > > But whatever. If it ever becomes *really* important, I guess > > we can flag this kind of behaviour from userspace. > > Important question: is there a standing NAK for the 'total' > parameter addition patch i did? You requested it and Linus didnt > like it ... and i've measured it and it's just a single > instruction in the whole kernel so it did not seem to be too bad > to me. Well I didn't request it so much as just being concerned about hard transitions in behaviour in general, and also the lack of an overall picture (which this patch improves a little, but doesn't solve -- only way to really do it is with explicit flags). > It might be wrong on the principle though, so will revert it if > needed, before it spreads into too many topics. I would say if Linus didn't like it, revert it. Do you use NFS with 1500 byte packets with a high speed network and really fast disks (or ramdisk)? Then maybe you can measure vectored write speedup with your patch over Salman's more basic one :)