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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-05-06 21:58:51 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-05-06 21:58:51 -0700 |
| commit | 18e8c134f4e984e6639e62846345192816f06d5c (patch) | |
| tree | 81bb46de14f020424716bd41915e831b07ce00c6 /include | |
| parent | d6bc0149d8f2300bffa03ea6fea3ca39744277a6 (diff) | |
| download | blackbird-obmc-linux-18e8c134f4e984e6639e62846345192816f06d5c.tar.gz blackbird-obmc-linux-18e8c134f4e984e6639e62846345192816f06d5c.zip | |
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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/skbuff.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 88d55395a27c..c9525bce80f6 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -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); |
