Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932202AbVI3Ew2 (ORCPT ); Fri, 30 Sep 2005 00:52:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932245AbVI3Ew2 (ORCPT ); Fri, 30 Sep 2005 00:52:28 -0400 Received: from sccrmhc14.comcast.net ([204.127.202.59]:23937 "EHLO sccrmhc14.comcast.net") by vger.kernel.org with ESMTP id S932202AbVI3Ew1 (ORCPT ); Fri, 30 Sep 2005 00:52:27 -0400 Message-Id: <200509300452.j8U4qKw17804@www.watkins-home.com> From: "Guy" To: "'Bill Davidsen'" Cc: "'Holger Kiehl'" , "'Mark Hahn'" , "'linux-raid'" , "'linux-kernel'" Subject: RE: Where is the performance bottleneck? Date: Fri, 30 Sep 2005 00:52:15 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook, Build 11.0.6353 In-Reply-To: <433AF75F.2060208@tmr.com> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 Thread-Index: AcXEaJ43BLlaJKpVRleHS1G4E/vAWQBESlvQ Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2064 Lines: 56 > -----Original Message----- > From: linux-raid-owner@vger.kernel.org [mailto:linux-raid- > owner@vger.kernel.org] On Behalf Of Bill Davidsen > Sent: Wednesday, September 28, 2005 4:05 PM > To: Guy > Cc: 'Holger Kiehl'; 'Mark Hahn'; 'linux-raid'; 'linux-kernel' > Subject: Re: Where is the performance bottleneck? > > Guy wrote: > > >In most of your results, your CPU usage is very high. Once you get to > about > >90% usage, you really can't do much else, unless you can improve the CPU > >usage. > > > That seems one of the problems with software RAID, the calculations are > done in the CPU and not dedicated hardware. As you move to the top end > drive hardware the CPU gets to be a limit. I don't remember off the top > of my head how threaded this code is, and if more CPUs will help. My old 500MHz P3 can xor at 1GB/sec. I don't think the RAID5 logic is the issue! Also, I have not seen hardware that fast! Or even half as fast. But I must admit, I have not seen a hardware RAID5 in a few years. :( 8regs : 918.000 MB/sec 32regs : 469.600 MB/sec pIII_sse : 994.800 MB/sec pII_mmx : 1102.400 MB/sec p5_mmx : 1152.800 MB/sec raid5: using function: pIII_sse (994.800 MB/sec) Humm.. It did not select the fastest? Guy > > I see you are using RAID-1 for your system stuff, did one of the tests > use RAID-0 over all the drives? Mirroring or XOR redundancy help > stability but hurt performance. Was the 270MB/s with RAID-0 or ??? > > -- > bill davidsen > CTO TMR Associates, Inc > Doing interesting things with small computers since 1979 > > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html - 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/