Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752219Ab0DZNso (ORCPT ); Mon, 26 Apr 2010 09:48:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7991 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751312Ab0DZNsn (ORCPT ); Mon, 26 Apr 2010 09:48:43 -0400 Message-ID: <4BD599A7.6090202@redhat.com> Date: Mon, 26 Apr 2010 16:48:23 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Dan Magenheimer CC: linux-kernel@vger.kernel.org, linux-mm@kvack.org, jeremy@goop.org, hugh.dickins@tiscali.co.uk, ngupta@vflare.org, JBeulich@novell.com, chris.mason@oracle.com, kurt.hackel@oracle.com, dave.mccracken@oracle.com, npiggin@suse.de, akpm@linux-foundation.org, riel@redhat.com Subject: Re: Frontswap [PATCH 0/4] (was Transcendent Memory): overview References: <20100422134249.GA2963@ca-server1.us.oracle.com> <4BD06B31.9050306@redhat.com> <53c81c97-b30f-4081-91a1-7cef1879c6fa@default> <4BD07594.9080905@redhat.com> <4BD16D09.2030803@redhat.com> <4BD1A74A.2050003@redhat.com> <4830bd20-77b7-46c8-994b-8b4fa9a79d27@default> <4BD1B427.9010905@redhat.com> <4BD336CF.1000103@redhat.com> <4BD43182.1040508@redhat.com> <4BD44E74.2020506@redhat.com> <7264e3c0-15fe-4b70-a3d8-2c36a2b934df@default 4BD52C4F.40505@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1319 Lines: 35 On 04/26/2010 03:45 PM, Dan Magenheimer wrote: >> dma engines are present on commodity hardware now: >> >> http://en.wikipedia.org/wiki/I/O_Acceleration_Technology >> >> I don't know if consumer machines have them, but servers certainly do. >> modprobe ioatdma. >> > They don't seem to have gained much ground in the FIVE YEARS > since the patch was first posted to Linux, have they? > Why do you say this? Servers have them and AFAIK networking uses them. There are other uses of the API in the code, but I don't know how much of this is for bulk copies. > Maybe it's because memory-to-memory copy using a CPU > is so fast (especially for page-ish quantities of data) > and is a small percentage of CPU utilization these days? > Copies take a small percentage of cpu because a lot of care goes into avoiding them, or placing them near the place where the copy is used. They certainly show up in high speed networking. A page-sized copy is small, but many of them will be expensive. -- error compiling committee.c: too many arguments to function -- 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/