Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8bdd663a authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: reorder fields of struct socket 



On x86_64, its rather unfortunate that "wait_queue_head_t wait"
field of "struct socket" spans two cache lines (assuming a 64
bytes cache line in current cpus)

offsetof(struct socket, wait)=0x30
sizeof(wait_queue_head_t)=0x18

This might explain why Kenny Chang noticed that his multicast workload
was performing bad with 64 bit kernels, since more cache lines ping pongs
were involved.

This litle patch moves "wait" field next "fasync_list" so that both
fields share a single cache line, to speedup sock_def_readable()

Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ff4fbd43

include/linux/net.h

+6 −2
Original line number Diff line number Diff line
@@ -129,11 +129,15 @@ struct socket { 
	socket_state		state;

	short			type;

	unsigned long		flags;

	const struct proto_ops	*ops;

	/*

	 * Please keep fasync_list & wait fields in the same cache line

	 */

	struct fasync_struct	*fasync_list;

	wait_queue_head_t	wait;



	struct file		*file;

	struct sock		*sk;

	wait_queue_head_t	wait;

	const struct proto_ops	*ops;

};



struct vm_area_struct;