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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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2
include/net/protocol.h
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@ -65,7 +65,7 @@ struct inet_protosw {
int protocol; /* This is the L4 protocol number. */
struct proto *prot;
struct proto_ops *ops;
const struct proto_ops *ops;
int capability; /* Which (if any) capability do
* we need to use this socket