From 19d5a26f5ef8de5dcb78799feaf404d717b1aac3 Mon Sep 17 00:00:00 2001 From: David Lebrun Date: Fri, 24 Mar 2017 10:46:26 +0100 Subject: [PATCH 1/2] ipv6: sr: expand skb head only if necessary To insert or encapsulate a packet with an SRH, we need a large enough skb headroom. Currently, we are using pskb_expand_head to inconditionally increase the size of the headroom by the amount needed by the SRH (and IPv6 header). If this reallocation is performed by another CPU than the one that initially allocated the skb, then when the initial CPU kfree the skb, it will enter the __slab_free slowpath, impacting performances. This patch replaces pskb_expand_head with skb_cow_head, that will reallocate the skb head only if the headroom is not large enough. Performances for SRH encapsulation before the patch: Result: OK: 7348320(c7347271+d1048) usec, 5000000 (1000byte,0frags) 680427pps 5443Mb/sec (5443416000bps) errors: 0 Performances after the patch: Result: OK: 5656067(c5655678+d388) usec, 5000000 (1000byte,0frags) 884006pps 7072Mb/sec (7072048000bps) errors: 0 Signed-off-by: David Lebrun Signed-off-by: David S. Miller --- net/ipv6/seg6_iptunnel.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index 85582257d3af8..dda2c5147ef0e 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -105,7 +105,7 @@ static int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh) hdrlen = (osrh->hdrlen + 1) << 3; tot_len = hdrlen + sizeof(*hdr); - err = pskb_expand_head(skb, tot_len, 0, GFP_ATOMIC); + err = skb_cow_head(skb, tot_len); if (unlikely(err)) return err; @@ -156,7 +156,7 @@ static int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh) hdrlen = (osrh->hdrlen + 1) << 3; - err = pskb_expand_head(skb, hdrlen, 0, GFP_ATOMIC); + err = skb_cow_head(skb, hdrlen); if (unlikely(err)) return err; From af4a2209b1344939eaac11f269c261d347cbc3ee Mon Sep 17 00:00:00 2001 From: David Lebrun Date: Fri, 24 Mar 2017 10:46:27 +0100 Subject: [PATCH 2/2] ipv6: sr: use dst_cache in seg6_input We already use dst_cache in seg6_output, when handling locally generated packets. We extend it in seg6_input, to also handle forwarded packets, and avoid unnecessary fib lookups. Performances for SRH encapsulation before the patch: Result: OK: 5656067(c5655678+d388) usec, 5000000 (1000byte,0frags) 884006pps 7072Mb/sec (7072048000bps) errors: 0 Performances after the patch: Result: OK: 4774543(c4774084+d459) usec, 5000000 (1000byte,0frags) 1047220pps 8377Mb/sec (8377760000bps) errors: 0 Signed-off-by: David Lebrun Signed-off-by: David S. Miller --- net/ipv6/seg6_iptunnel.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index dda2c5147ef0e..30ef1d1d182e9 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -237,6 +237,9 @@ static int seg6_do_srh(struct sk_buff *skb) static int seg6_input(struct sk_buff *skb) { + struct dst_entry *orig_dst = skb_dst(skb); + struct dst_entry *dst = NULL; + struct seg6_lwt *slwt; int err; err = seg6_do_srh(skb); @@ -245,8 +248,30 @@ static int seg6_input(struct sk_buff *skb) return err; } + slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate); + +#ifdef CONFIG_DST_CACHE + preempt_disable(); + dst = dst_cache_get(&slwt->cache); + preempt_enable(); +#endif + skb_dst_drop(skb); - ip6_route_input(skb); + + if (!dst) { + ip6_route_input(skb); +#ifdef CONFIG_DST_CACHE + dst = skb_dst(skb); + if (!dst->error) { + preempt_disable(); + dst_cache_set_ip6(&slwt->cache, dst, + &ipv6_hdr(skb)->saddr); + preempt_enable(); + } +#endif + } else { + skb_dst_set(skb, dst); + } return dst_input(skb); }