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packet: reorder a member in packet_ring_buffer 

There's a 4 byte hole in packet_ring_buffer structure before
prb_bdqc, that can be filled with 'pending' member, thus we can
reduce the overall structure size from 224 bytes to 216 bytes.
This also has the side-effect, that in struct packet_sock 2*4 byte
holes after the embedded packet_ring_buffer members are removed,
and overall, packet_sock can be reduced by 1 cacheline:

Before: size: 1344, cachelines: 21, members: 24
After:  size: 1280, cachelines: 20, members: 24

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2013-04-19 06:12:28 +00:00 committed by David S. Miller
parent 660f7d2229
commit 0578edc560
1 changed files with 3 additions and 1 deletions
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4
net/packet/internal.h
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@ -54,6 +54,7 @@ struct pgv {
struct packet_ring_buffer {
struct pgv *pg_vec;
unsigned int head;
unsigned int frames_per_block;
unsigned int frame_size;
@ -63,8 +64,9 @@ struct packet_ring_buffer {
unsigned int pg_vec_pages;
unsigned int pg_vec_len;
struct tpacket_kbdq_core prb_bdqc;
atomic_t pending;
struct tpacket_kbdq_core prb_bdqc;
};
extern struct mutex fanout_mutex;