From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263893AbUEHRuo (ORCPT ); Sat, 8 May 2004 13:50:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264019AbUEHRuo (ORCPT ); Sat, 8 May 2004 13:50:44 -0400 Received: from ns.clanhk.org ([69.93.101.154]:26314 "EHLO mail.clanhk.org") by vger.kernel.org with ESMTP id S263893AbUEHRub (ORCPT ); Sat, 8 May 2004 13:50:31 -0400 Message-ID: <409D1D86.6050907@clanhk.org> Date: Sat, 08 May 2004 12:48:54 -0500 From: "J. Ryan Earl" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6b) Gecko/20031205 Thunderbird/0.4 X-Accept-Language: en-us, en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: AMD64 and RAID6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I noticed the following in my dmesg: raid5: measuring checksumming speed generic_sse: 6604.000 MB/sec raid5: using function: generic_sse (6604.000 MB/sec) raid6: int64x1 1847 MB/s raid6: int64x2 2753 MB/s raid6: int64x4 2878 MB/s raid6: int64x8 1902 MB/s raid6: sse2x1 1015 MB/s raid6: sse2x2 1488 MB/s raid6: sse2x4 1867 MB/s raid6: using algorithm sse2x4 (1867 MB/s) md: raid6 personality registered as nr 8 md: md driver 0.90.0 MAX_MD_DEVS=256, MD_SB_DISKS=27 Why doesn't RAID6 use the int64x4 algorithm in this situation? What is the motivation of setting the 'prefer field' on the sse algorithms and not on the integer based algorithms? From drivers/md/raid6.h: /* Routine choices */ struct raid6_calls { void (*gen_syndrome)(int, size_t, void **); int (*valid)(void); /* Returns 1 if this routine set is usable */ const char *name; /* Name of this routine set */ int prefer; /* Has special performance attribute */ }; -ryan