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Date:      Wed, 17 May 2000 10:25:16 -0700
From:      Alfred Perlstein <bright@wintelcom.net>
To:        Joy Ganguly <joy.ganguly@usa.net>
Cc:        freebsd-hackers@FreeBSD.ORG
Subject:   Re: Question about file write????
Message-ID:  <20000517102516.B14968@fw.wintelcom.net>
In-Reply-To: <20000517160746.12768.qmail@www0a.netaddress.usa.net>; from joy.ganguly@usa.net on Wed, May 17, 2000 at 10:07:46AM -0600
References:  <20000517160746.12768.qmail@www0a.netaddress.usa.net>

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* Joy Ganguly <joy.ganguly@usa.net> [000517 09:41] wrote:
> 
> hi all, 
> 
> i have written a special ioctl which writes data into a file from a buffer in
> kernel memory. it invokes fo->fo_write() and involves one copy from kernel
> mem
> to disk cache. however this takes substantially more time than an ordinary
> write which copies from user space to the disk cache. any explanations??? 

What are you using for your kernel to kernel copy?

(copyin and friends are hand optimized for great speed when copying
from/to userspace)


-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."


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