Commit 18e8c134 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

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
......@@ -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);
......
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