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Commit 18e8c134 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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net: Increase NET_SKB_PAD to 64 bytes 



eth_type_trans() & get_rps_cpus() currently need two 64bytes cache
lines in packet to compute rxhash.

Increasing NET_SKB_PAD from 32 to 64 reduces the need to one cache
line only, and makes RPS faster.

NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d6bc0149

include/linux/skbuff.h

+4 −1
Original line number Diff line number Diff line
@@ -1361,9 +1361,12 @@ static inline int skb_network_offset(const struct sk_buff *skb) 
 *

 * Various parts of the networking layer expect at least 32 bytes of

 * headroom, you should not reduce this.

 * With RPS, we raised NET_SKB_PAD to 64 so that get_rps_cpus() fetches span

 * a 64 bytes aligned block to fit modern (>= 64 bytes) cache line sizes

 * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)

 */

#ifndef NET_SKB_PAD

#define NET_SKB_PAD	32

#define NET_SKB_PAD	64

#endif



extern int ___pskb_trim(struct sk_buff *skb, unsigned int len);