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Date:      Thu, 27 Oct 2005 12:37:29 +0200
From:      "Poul-Henning Kamp" <phk@phk.freebsd.dk>
To:        David Xu <davidxu@freebsd.org>
Cc:        current@freebsd.org, Marian Hettwer <MH@kernel32.de>
Subject:   Re: MySQL Performance 6.0rc1 
Message-ID:  <21905.1130409449@critter.freebsd.dk>
In-Reply-To: Your message of "Thu, 27 Oct 2005 16:29:23 %2B0800." <43608FE3.9050406@freebsd.org> 

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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.



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