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[NET]: move struct proto_ops to const

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I noticed that some of 'struct proto_ops' used in the kernel may share
a cache line used by locks or other heavily modified data. (default
linker alignement is 32 bytes, and L1_CACHE_LINE is 64 or 128 at
least)

This patch makes sure a 'struct proto_ops' can be declared as const,
so that all cpus can share all parts of it without false sharing.

This is not mandatory : a driver can still use a read/write structure
if it needs to (and eventually a __read_mostly)

I made a global stubstitute to change all existing occurences to make
them const.

This should reduce the possibility of false sharing on SMP, and
speedup some socket system calls.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2005-12-22 12:49:22 -08:00 • committed by David S. Miller
parent 77d76ea310
commit 90ddc4f047
33 changed files with 66 additions and 66 deletions
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4
include/linux/net.h
View file

@ -107,7 +107,7 @@ enum sock_type {
struct socket {
socket_state state;
unsigned long flags;
struct proto_ops *ops;
const struct proto_ops *ops;
struct fasync_struct *fasync_list;
struct file *file;
struct sock *sk;
@ -260,7 +260,7 @@ SOCKCALL_WRAP(name, recvmsg, (struct kiocb *iocb, struct socket *sock, struct ms
SOCKCALL_WRAP(name, mmap, (struct file *file, struct socket *sock, struct vm_area_struct *vma), \
(file, sock, vma)) \
\
static struct proto_ops name##_ops = { \
static const struct proto_ops name##_ops = { \
.family = fam, \
.owner = THIS_MODULE, \
.release = __lock_##name##_release, \