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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Changli Gao <xiaosuo@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Matthew Wilcox <matthew@wil.cx>, Arnd Bergmann <arnd@arndb.de>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org
Subject: Re: [PATCH] fs: add FD_CLOFORK and O_CLOFORK
Date: Sat, 07 May 2011 07:25:45 +0200	[thread overview]
Message-ID: <1304745945.2821.601.camel@edumazet-laptop> (raw)
In-Reply-To: <1304743740-3405-1-git-send-email-xiaosuo@gmail.com>

Le samedi 07 mai 2011 à 12:49 +0800, Changli Gao a écrit :
> If FD_CLOFORK is 1, when a fork occurs, the corresponding file descriptor
> will be closed for the child process. IOW, the file descriptor isn't
> inheritable.
> 
> FD_CLOFORK is used as IBM does.

Is it part of a standard, and what could be the use for such thing ?
Why had we wait 2011 to add it in linux ?

> 
> O_CLOFORK is also added to avoid the additional fcntl(2) after open(2).
> 
> Signed-off-by: Changli Gao <xiaosuo@gmail.com>


Your implementation has some peformance implication.

close_on_exec and close_on_fork bit for a given fd would be on separate
cache lines. So you add a cost on threaded programs for open()/close()

[ Yes, we apparently clear close_on_exec bit in close()... we could let
it untouched and make flush_old_files() aware of that ]




WARNING: multiple messages have this Message-ID (diff)
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Changli Gao <xiaosuo@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Matthew Wilcox <matthew@wil.cx>, Arnd Bergmann <arnd@arndb.de>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org
Subject: Re: [PATCH] fs: add FD_CLOFORK and O_CLOFORK
Date: Sat, 07 May 2011 07:25:45 +0200	[thread overview]
Message-ID: <1304745945.2821.601.camel@edumazet-laptop> (raw)
In-Reply-To: <1304743740-3405-1-git-send-email-xiaosuo@gmail.com>

Le samedi 07 mai 2011 à 12:49 +0800, Changli Gao a écrit :
> If FD_CLOFORK is 1, when a fork occurs, the corresponding file descriptor
> will be closed for the child process. IOW, the file descriptor isn't
> inheritable.
> 
> FD_CLOFORK is used as IBM does.

Is it part of a standard, and what could be the use for such thing ?
Why had we wait 2011 to add it in linux ?

> 
> O_CLOFORK is also added to avoid the additional fcntl(2) after open(2).
> 
> Signed-off-by: Changli Gao <xiaosuo@gmail.com>


Your implementation has some peformance implication.

close_on_exec and close_on_fork bit for a given fd would be on separate
cache lines. So you add a cost on threaded programs for open()/close()

[ Yes, we apparently clear close_on_exec bit in close()... we could let
it untouched and make flush_old_files() aware of that ]



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  reply	other threads:[~2011-05-07  6:18 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-07  4:49 [PATCH] fs: add FD_CLOFORK and O_CLOFORK Changli Gao
2011-05-07  5:25 ` Eric Dumazet [this message]
2011-05-07  5:25   ` Eric Dumazet
2011-05-07 10:09   ` Changli Gao
2011-05-07  6:06 ` Eric Dumazet
2011-05-07  6:22   ` Changli Gao
2011-05-07  6:29     ` Eric Dumazet
2011-05-07 10:10       ` Changli Gao
2011-05-07 11:41       ` Geert Uytterhoeven
2011-05-07 12:32         ` Eric Dumazet
2011-05-07 12:32           ` Eric Dumazet

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