From owner-freebsd-current@FreeBSD.ORG  Thu Oct 27 10:37:31 2005
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
X-Original-To: current@freebsd.org
Delivered-To: freebsd-current@FreeBSD.ORG
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id CC91616A41F;
	Thu, 27 Oct 2005 10:37:31 +0000 (GMT)
	(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 74E8243D45;
	Thu, 27 Oct 2005 10:37:31 +0000 (GMT)
	(envelope-from phk@critter.freebsd.dk)
Received: from critter.freebsd.dk (unknown [192.168.48.2])
	by phk.freebsd.dk (Postfix) with ESMTP id A363BBC7A;
	Thu, 27 Oct 2005 10:37:29 +0000 (UTC)
To: David Xu <davidxu@freebsd.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Thu, 27 Oct 2005 16:29:23 +0800."
	<43608FE3.9050406@freebsd.org> 
Date: Thu, 27 Oct 2005 12:37:29 +0200
Message-ID: <21905.1130409449@critter.freebsd.dk>
Sender: phk@critter.freebsd.dk
Cc: current@freebsd.org, Marian Hettwer <MH@kernel32.de>
Subject: Re: MySQL Performance 6.0rc1 
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 27 Oct 2005 10:37:31 -0000

In message <43608FE3.9050406@freebsd.org>, David Xu writes:
>Poul-Henning Kamp wrote:
>> In message <43607DD5.3020708@freebsd.org>, David Xu writes:
>> 
>>>Check gettimeofday syscall, it follows every I/O syscall, I think
>>>our gettimeofday is tooooooo expensive, if we can directly get time from
>>>memory, the performance will be improved further.
>> 
>> Why would anybody take a timestamp at all I/O syscalls ? 
>> 
>> "I wonder why my car can only go 30 km/h with the trunk full of concrete" ?
>> 
>> In a data base application I could possibly understand a timestamp
>> after every write.
>> 
>> But after _all_ I/O syscalls ?  That's just plain stupid...
>
>Don't panic, I agree that is stupid code, but I can not change it, it
>is not written by me, sorry!

I'm not panicing, I'm merely pointing out that we should not optimize
performance after bogus code but rather try to improve it.

-- 
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.