From owner-cvs-src@FreeBSD.ORG Sun Jan 6 17:13:02 2008 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0BEC416A468; Sun, 6 Jan 2008 17:13:02 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222]) by mx1.freebsd.org (Postfix) with ESMTP id AAC6713C4CE; Sun, 6 Jan 2008 17:13:01 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (unknown [192.168.61.3]) by phk.freebsd.dk (Postfix) with ESMTP id 4C81417106; Sun, 6 Jan 2008 17:13:00 +0000 (UTC) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.14.2/8.14.2) with ESMTP id m06HCxjf001768; Sun, 6 Jan 2008 17:13:00 GMT (envelope-from phk@critter.freebsd.dk) To: Colin Percival From: "Poul-Henning Kamp" In-Reply-To: Your message of "Sun, 06 Jan 2008 04:39:55 PST." <4780CC1B.8090708@freebsd.org> Date: Sun, 06 Jan 2008 17:12:59 +0000 Message-ID: <1767.1199639579@critter.freebsd.dk> Sender: phk@critter.freebsd.dk Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/usr.sbin/gstat gstat.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 06 Jan 2008 17:13:02 -0000 In message <4780CC1B.8090708@freebsd.org>, Colin Percival writes: >Poul-Henning Kamp wrote: >> When the ms/req fields exceed 1 second, drop the fractions to fit more digits. >> >> This is unfortunately necessary with some flash based devices which can >> get hundreds of seconds behind with softupdates enabled. > >I'm curious, why is this an issue with flash devices? Given their famous >ability to perform large numbers of transactions per second, I would have >expected flash-based drives to be the least likely to have this problem. The problem is flash-devices which are built (mostly) for cameras, their (cheap-ass) flash-adaptation-layer performs great for physically sequential writes for big files, and they fall totally apart with random writes to things like UFS/FFS inodes and bitmaps. Pretty much all of the layout optimizations in UFS/FFS are pessimizations for Flash devices. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.