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

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Message-Id: <200703081929.58265.dada1@cosmosbay.com>
Date:	Thu, 8 Mar 2007 19:29:57 +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] VFS : Delay the dentry name generation on sockets and pipes.

Hi Andrew

I am sorry, my previous patch had a /proc/*/fd/ in a comment, so the */ closed 
the comment and fs/dcache.c could not compile.

Could you please put this 'final-final' version in mm for testing ?

Thank's to all contributors, sorry for the noise.

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

3) Use this new 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>

 Documentation/filesystems/Locking |    2 ++
 Documentation/filesystems/vfs.txt |   12 +++++++++++-
 fs/dcache.c                       |   10 ++++++++++
 fs/pipe.c                         |   15 +++++++++------
 include/linux/dcache.h            |    1 +
 net/socket.c                      |   17 ++++++++++-------
 6 files changed, 43 insertions(+), 14 deletions(-)

View attachment "introduce_d_dname.patch" of type "text/plain" (5921 bytes)