linux-kernel - Re: [patch] epoll use a single inode ...

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Date:	Wed, 7 Mar 2007 18:36:29 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Avi Kivity <avi@...o.co.il>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [patch] epoll use a single inode ...

(resending with a more convenient attachment)

Please find enclosed the following patch, to prepare this path.

[PATCH] 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 be able to provide a dentry name 
for special filesystems. It is called without locks.

Future patches (if we succeed in having one common dentry for all pipes) 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/...
We also avoid mntput()/mntget() on sock_mnt

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/...
We also avoid mntput()/mntget() on pipe_mnt

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>

 fs/dcache.c            |    3 +++
 fs/pipe.c              |   16 +++++++++++-----
 include/linux/dcache.h |    1 +
 net/socket.c           |   15 +++++++++++----
 4 files changed, 26 insertions(+), 9 deletions(-)

View attachment "introduce_d_dname.patch" of type "text/plain" (3785 bytes)