From owner-freebsd-bugs@FreeBSD.ORG Wed Oct 19 23:07:15 2011 Return-Path: Delivered-To: freebsd-bugs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5AAE01065670 for ; Wed, 19 Oct 2011 23:07:15 +0000 (UTC) (envelope-from freebsd@damnhippie.dyndns.org) Received: from qmta04.emeryville.ca.mail.comcast.net (qmta04.emeryville.ca.mail.comcast.net [76.96.30.40]) by mx1.freebsd.org (Postfix) with ESMTP id 41C798FC15 for ; Wed, 19 Oct 2011 23:07:14 +0000 (UTC) Received: from omta08.emeryville.ca.mail.comcast.net ([76.96.30.12]) by qmta04.emeryville.ca.mail.comcast.net with comcast id mmfj1h0030FhH24A4mtyoN; Wed, 19 Oct 2011 22:53:58 +0000 Received: from damnhippie.dyndns.org ([24.8.232.202]) by omta08.emeryville.ca.mail.comcast.net with comcast id mmtd1h01h4NgCEG8Umtepa; Wed, 19 Oct 2011 22:53:38 +0000 Received: from [172.22.42.240] (revolution.hippie.lan [172.22.42.240]) by damnhippie.dyndns.org (8.14.3/8.14.3) with ESMTP id p9JMs24v026782; Wed, 19 Oct 2011 16:54:02 -0600 (MDT) (envelope-from freebsd@damnhippie.dyndns.org) From: Ian Lepore To: jilles@FreeBSD.org In-Reply-To: <201110192240.p9JMe9J0022649@freefall.freebsd.org> References: <201110192240.p9JMe9J0022649@freefall.freebsd.org> Content-Type: text/plain Date: Wed, 19 Oct 2011 16:54:02 -0600 Message-Id: <1319064842.2184.47.camel@revolution.hippie.lan> Mime-Version: 1.0 X-Mailer: Evolution 2.26.0 FreeBSD GNOME Team Port Content-Transfer-Encoding: 7bit Cc: freebsd-bugs@FreeBSD.org Subject: Re: bin/161756: [patch] sh(1) /bin/sh: read files in 1024-byte chunks rather than 1023 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Oct 2011 23:07:15 -0000 I'm sorry to say I don't have any performance numbers, and this change isn't really important enough to me to spend any time generating them. I actually noticed the 1023-byte IOs while debugging a problem that led me to instrument ffs_read() activity on executable files, and the change to a power-of-2-sized IO was so simple that I took a few extra minutes to submit a PR for it. It takes our 180mhz ARM platforms unreasonably long to run all the /etc/rc.d scripts, over two minutes. If this change buys back a couple seconds from that it'd be nice, but the real motivation for the patch wasn't that I expected the performance change to blow me away, it was just that something deep in my core rebels at knowing there's a 1023 byte IO going on when it could just as easily be 1024. I don't know of any hardware devices that work better with a 1023 byte IO size. :) -- Ian On Wed, 2011-10-19 at 22:40 +0000, jilles@FreeBSD.org wrote: > Synopsis: [patch] sh(1) /bin/sh: read files in 1024-byte chunks rather than 1023 > > State-Changed-From-To: open->feedback > State-Changed-By: jilles > State-Changed-When: Wed Oct 19 22:33:38 UTC 2011 > State-Changed-Why: > Although this change looks like an improvement, it does not seem > fully satisfying. I would like to see performance numbers for the > change on your slow embedded platform. Also, why use 1023 or 1024? > Another buffer size may be better. > > > Responsible-Changed-From-To: freebsd-bugs->jilles > Responsible-Changed-By: jilles > Responsible-Changed-When: Wed Oct 19 22:33:38 UTC 2011 > Responsible-Changed-Why: > Take. > > http://www.freebsd.org/cgi/query-pr.cgi?pr=161756