Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261405AbUDWVXD (ORCPT ); Fri, 23 Apr 2004 17:23:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261474AbUDWVXD (ORCPT ); Fri, 23 Apr 2004 17:23:03 -0400 Received: from kinesis.swishmail.com ([209.10.110.86]:29960 "EHLO kinesis.swishmail.com") by vger.kernel.org with ESMTP id S261405AbUDWVW7 (ORCPT ); Fri, 23 Apr 2004 17:22:59 -0400 Message-ID: <408989E3.5010009@techsource.com> Date: Fri, 23 Apr 2004 17:25:55 -0400 From: Timothy Miller MIME-Version: 1.0 To: Ben Greear CC: root@chaos.analogic.com, =?ISO-8859-1?Q?M=E5ns_Rullg=E5rd?= , linux-kernel@vger.kernel.org Subject: Re: File system compression, not at the block layer References: <40898730.50009@candelatech.com> In-Reply-To: <40898730.50009@candelatech.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1105 Lines: 30 Ben Greear wrote: > Richard B. Johnson wrote: > >> Actually not. You need a FIFO to cache your bits into buffers of bytes >> anyway. Depending upon the length of the FIFO, you can "rubber-band" a >> lot of rotational latency. When you are dealing with a lot of drives, >> you are never going to have all the write currents turn on at the same >> time anyway because they are (very) soft-sectored, i.e., block >> replacement, etc. > > > Wouldn't this pretty much guarantee worst-case latency scenario for > reading, since > on average at least one of your 32 disks is going to require a full > rotation > (and probably a seek) to find it's bit? Only for the first bit of a block. For large streams of reads, the fifos will keep things going, except for occasionally as drives drift in their relative rotation positions which can cause some delays. - 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/