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From: Davide Libenzi <davidel@xmailserver.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@tv-sign.ru>
Subject: Re: [patch 2/13] signal/timer/event fds v6 - signalfd core ...
Date: Sun, 18 Mar 2007 17:22:48 -0700 (PDT)	[thread overview]
Message-ID: <Pine.LNX.4.64.0703181720410.5482@alien.or.mcafeemobile.com> (raw)
In-Reply-To: <200703190045.24605.arnd@arndb.de>

On Mon, 19 Mar 2007, Arnd Bergmann wrote:

> On Sunday 18 March 2007, Davide Libenzi wrote:
> > bah, __put_user is basically a move, so I don't think that efficency would 
> > be that different (assuming that it'd matter in this case). The only thing 
> > many __put_user do, is increase the exception table sizes.
> 
> The cost of user access functions varies a lot depending on the
> architectures. Those platforms with a 4G/4G split e.g. need to do more
> than a simple move, and for s390 it may even come down to an indirect
> function call, which incurs significant register pressure.

Heh, I'd like ppl to agree on this, because I clearly remember in having 
an argoument with Andrew for the same thing, where I was doing stack setup 
plus copy_to_user() ;)



- Davide



  reply	other threads:[~2007-03-19  0:24 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-16  0:22 Davide Libenzi
2007-03-17 21:35 ` Arnd Bergmann
2007-03-17 21:50   ` Arnd Bergmann
2007-03-18  4:56   ` Stephen Rothwell
2007-03-18 20:31   ` Davide Libenzi
2007-03-18 23:45     ` Arnd Bergmann
2007-03-19  0:22       ` Davide Libenzi [this message]
2007-03-19 17:20 ` Eric W. Biederman
2007-03-19 18:53   ` Davide Libenzi
2007-03-19 19:08     ` Eric W. Biederman
2007-03-19 19:11       ` Davide Libenzi
2007-03-19 20:36     ` Oleg Nesterov
2007-03-19 22:33       ` Davide Libenzi
2007-03-19 22:53         ` Oleg Nesterov
2007-03-19 23:28           ` Oleg Nesterov
2007-03-19 23:34             ` Davide Libenzi

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