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To: Kirk McKusick <mckusick@chez.mckusick.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 05 Jun 2006 10:00:24 PDT."
	<200606051700.k55H0OeJ092393@chez.mckusick.com> 
Date: Mon, 05 Jun 2006 19:08:38 +0200
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Cc: arch@freebsd.org, Garrett Wollman <wollman@khavrinen.csail.mit.edu>,
	rwatson@freebsd.org
Subject: Re: Why use `thread' as an argument of Syscalls? 
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In message <200606051700.k55H0OeJ092393@chez.mckusick.com>, Kirk McKusick write
s:

>Your above analysis is correct. When we made the pass over the code
>base to eliminate all references to "u." we had also hoped to get rid
>of all references to "curproc". While we were successful with the former,
>it eventually became clear that the latter was not practical. But by
>that time, the convention of passing the current process pointer to
>Syscall was established, and removing it did not seem to be worth 
>the effort.

It would be a good Junior Kernel Hacker project to try to replace
these passed arguments with curproc and see if a measurable difference
in performance is obtained.

-- 
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.