From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932442AbWGAI1i (ORCPT ); Sat, 1 Jul 2006 04:27:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932710AbWGAI1i (ORCPT ); Sat, 1 Jul 2006 04:27:38 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:30912 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S932442AbWGAI1h (ORCPT ); Sat, 1 Jul 2006 04:27:37 -0400 Subject: Re: [PATCH] Add memcpy_nc, a copy routine that tries to keep cache pressure down From: Arjan van de Ven To: "Bryan O'Sullivan" Cc: linux-kernel@vger.kernel.org, davem@davemloft.net In-Reply-To: References: Content-Type: text/plain Date: Sat, 01 Jul 2006 10:27:34 +0200 Message-Id: <1151742454.3195.10.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2006-06-30 at 21:56 -0700, Bryan O'Sullivan wrote: > This copy routine is memcpy-compatible, but on some architectures will use > cache-bypassing loads to avoid bringing the source data into the cache. > > One case where this is useful is when a device issues a DMA to a memory > region, and the CPU must copy the DMAed data elsewhere before doing any > work with it. Since the source data is read-once, write-never from the > CPU's perspective, caching those addresses can only evict potentially > useful data. > > We provide an x86_64 implementation that uses SSE non-temporal loads, > and a generic version that falls back to plain memcpy. Hi, can we give this a more descriptive name please? Say memcpy_cachebypass() or something? "_nc" doesn't say a lot of things to many people... which means it'll either not get used when it should, or it gets used when it shouldn't.... Greetings, Arjan van de Ven