linux-kernel - [PATCH, take3] VFS : Delay the dentry name generation on sockets and pipes.

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Message-id: <200703100221.32894.dada1@cosmosbay.com>
Date:	Sat, 10 Mar 2007 02:21:32 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Christoph Hellwig <hch@...radead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH, take3] VFS : Delay the dentry name generation on sockets and
 pipes.

Hi Andrew

Please find take3 of this patch : Linus suggested to introduce a helper 
function to factorize work done by most d_dname() implementations.

Thank you

[PATCH] VFS : Delay the dentry name generation on sockets and pipes.

1) Introduces a new method in 'struct dentry_operations'. This method called 
d_dname() might be called from d_path() to build a pathname 
for special filesystems. It is called without locks.

Future patches (if we succeed in having one common dentry for all 
pipes/sockets) may need to change prototype of this method, but we now use :
char *d_dname(struct dentry *dentry, char *buffer, int buflen);

2) Adds a dynamic_dname() helper function that eases d_dname() implementations

3) Defines d_dname method for sockets : No more sprintf() at socket creation. 
This is delayed up to the moment someone does an access to /proc/pid/fd/...

4) Defines d_dname method for pipes : No more sprintf() at pipe creation.
This is delayed up to the moment someone does an access to /proc/pid/fd/...

A benchmark consisting of 1.000.000 calls to pipe()/close()/close() gives a 
*nice* speedup on my Pentium(M) 1.6 Ghz :

3.090 s instead of 3.450 s

Signed-off-by: Eric Dumazet <dada1@...mosbay.com>
Acked-by: Christoph Hellwig <hch@...radead.org>
Acked-by: Linus Torvalds <torvalds@...ux-foundation.org>

View attachment "introduce_d_dname_3.patch" of type "text/plain" (7560 bytes)