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These flush checks are used currently in all tcp flows and in some UDP flows in GRO. These checks need to be done only once and only against the found p skb, since they only affect flush and not same_flow. Leveraging the previous commit in the series, in which correct network header offsets are saved for both outer and inner network headers - allowing these checks to be done only once, in tcp_gro_receive and udp_gro_receive_segment. As a result, NAPI_GRO_CB(p)->flush is not used at all. In addition, flush_id checks are more declarative and contained in inet_gro_flush, thus removing the need for flush_id in napi_gro_cb. This results in less parsing code for UDP flows and non-loop flush tests for TCP flows. To make sure results are not within noise range - I've made netfilter drop all TCP packets, and measured CPU performance in GRO (in this case GRO is responsible for about 50% of the CPU utilization). L3 flush/flush_id checks are not relevant to UDP connections where skb_gro_receive_list is called. The only code change relevant to this flow is inet_gro_receive. The rest of the code parsing this flow stays the same. All concurrent connections tested are with the same ip srcaddr and dstaddr. perf top while replaying 64 concurrent IP/UDP connections (UDP fwd flow): net-next: 3.03% [kernel] [k] inet_gro_receive patch applied: 2.78% [kernel] [k] inet_gro_receive perf top while replaying encapsulated load - 64 concurrent IP/IP/UDP connections (rx-gro-list and rx-udp-gro-forwarding are enabled): net-next: 10.50% [kernel] [k] inet_gro_receive patch applied: 8.19% [kernel] [k] inet_gro_receive perf top while replaying 64 parallel IP/TCP streams merging in GRO: (gro_network_flush is compiled inline to tcp_gro_receive) net-next: 6.94% [kernel] [k] inet_gro_receive 3.02% [kernel] [k] tcp_gro_receive patch applied: 4.27% [kernel] [k] tcp_gro_receive 4.22% [kernel] [k] inet_gro_receive perf top while replaying 64 parallel IP/IP/TCP streams merging in GRO (same results for any encapsulation, in this case inet_gro_receive is top offender in net-next) net-next: 10.09% [kernel] [k] inet_gro_receive 2.08% [kernel] [k] tcp_gro_receive patch applied: 6.97% [kernel] [k] inet_gro_receive 3.68% [kernel] [k] tcp_gro_receive Signed-off-by: Richard Gobert --- include/net/gro.h | 66 ++++++++++++++++++++++++++++++++++++++---- net/core/gro.c | 4 --- net/ipv4/af_inet.c | 41 +------------------------- net/ipv4/tcp_offload.c | 15 ++-------- net/ipv4/udp_offload.c | 16 +++------- net/ipv6/ip6_offload.c | 11 ------- 6 files changed, 67 insertions(+), 86 deletions(-) diff --git a/include/net/gro.h b/include/net/gro.h index a1cc8e8c2ebd..c1f80f1156d6 100644 --- a/include/net/gro.h +++ b/include/net/gro.h @@ -36,15 +36,15 @@ struct napi_gro_cb { /* This is non-zero if the packet cannot be merged with the new skb. */ u16 flush; - /* Save the IP ID here and check when we get to the transport layer */ - u16 flush_id; - /* Number of segments aggregated. */ u16 count; /* Used in ipv6_gro_receive() and foo-over-udp and esp-in-udp */ u16 proto; + /* used to support CHECKSUM_COMPLETE for tunneling protocols */ + __wsum csum; + /* Used in napi_gro_cb::free */ #define NAPI_GRO_FREE 1 #define NAPI_GRO_FREE_STOLEN_HEAD 2 @@ -85,9 +85,6 @@ struct napi_gro_cb { u8 is_flist:1; ); - /* used to support CHECKSUM_COMPLETE for tunneling protocols */ - __wsum csum; - /* L3 offsets */ union { struct { @@ -443,6 +440,63 @@ static inline __wsum ip6_gro_compute_pseudo(const struct sk_buff *skb, skb_gro_len(skb), proto, 0)); } +static inline int inet_gro_flush(const struct iphdr *iph, const struct iphdr *iph2, + struct sk_buff *p, bool outer) +{ + const u32 id = ntohl(*(__be32 *)&iph->id); + const u32 id2 = ntohl(*(__be32 *)&iph2->id); + const u16 flush_id = (id >> 16) - (id2 >> 16); + const u16 count = NAPI_GRO_CB(p)->count; + const u32 df = id & IP_DF; + u32 is_atomic; + int flush; + + /* All fields must match except length and checksum. */ + flush = (iph->ttl ^ iph2->ttl) | (iph->tos ^ iph2->tos) | (df ^ (id2 & IP_DF)); + + if (outer && df) + return flush; + + /* When we receive our second frame we can make a decision on if we + * continue this flow as an atomic flow with a fixed ID or if we use + * an incrementing ID. + */ + NAPI_GRO_CB(p)->is_atomic |= (count == 1 && df && flush_id == 0); + is_atomic = (df && NAPI_GRO_CB(p)->is_atomic) - 1; + + return flush | (flush_id ^ (count & is_atomic)); +} + +static inline int ipv6_gro_flush(const struct ipv6hdr *iph, const struct ipv6hdr *iph2) +{ + /* */ + __be32 first_word = *(__be32 *)iph ^ *(__be32 *)iph2; + + /* Flush if Traffic Class fields are different. */ + return !!((first_word & htonl(0x0FF00000)) | + (__force __be32)(iph->hop_limit ^ iph2->hop_limit)); +} + +static inline int gro_network_flush(const void *th, const void *th2, struct sk_buff *p, int off) +{ + const bool encap_mark = NAPI_GRO_CB(p)->encap_mark; + int flush = 0; + int i; + + for (i = 0; i <= encap_mark; i++) { + const u16 diff = off - NAPI_GRO_CB(p)->network_offsets[i]; + const void *nh = th - diff; + const void *nh2 = th2 - diff; + + if (((struct iphdr *)nh)->version == 6) + flush |= ipv6_gro_flush(nh, nh2); + else + flush |= inet_gro_flush(nh, nh2, p, i != encap_mark); + } + + return flush; +} + int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb); /* Pass the currently batched GRO_NORMAL SKBs up to the stack. */ diff --git a/net/core/gro.c b/net/core/gro.c index b2156e6cc4ad..3bfdfefe4a24 100644 --- a/net/core/gro.c +++ b/net/core/gro.c @@ -89,7 +89,6 @@ void dev_remove_offload(struct packet_offload *po) } EXPORT_SYMBOL(dev_remove_offload); - int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb) { struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb); @@ -330,8 +329,6 @@ static void gro_list_prepare(const struct list_head *head, list_for_each_entry(p, head, list) { unsigned long diffs; - NAPI_GRO_CB(p)->flush = 0; - if (hash != skb_get_hash_raw(p)) { NAPI_GRO_CB(p)->same_flow = 0; continue; @@ -471,7 +468,6 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff sizeof(u32))); /* Avoid slow unaligned acc */ *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0; NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb); - NAPI_GRO_CB(skb)->is_atomic = 1; NAPI_GRO_CB(skb)->count = 1; if (unlikely(skb_is_gso(skb))) { NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs; diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 6546bf376b24..af094aecf38c 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1481,7 +1481,6 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb) struct sk_buff *p; unsigned int hlen; unsigned int off; - unsigned int id; int flush = 1; int proto; @@ -1507,13 +1506,10 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb) goto out; NAPI_GRO_CB(skb)->proto = proto; - id = ntohl(*(__be32 *)&iph->id); - flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (id & ~IP_DF)); - id >>= 16; + flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (ntohl(*(__be32 *)&iph->id) & ~IP_DF)); list_for_each_entry(p, head, list) { struct iphdr *iph2; - u16 flush_id; if (!NAPI_GRO_CB(p)->same_flow) continue; @@ -1530,43 +1526,8 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb) NAPI_GRO_CB(p)->same_flow = 0; continue; } - - /* All fields must match except length and checksum. */ - NAPI_GRO_CB(p)->flush |= - (iph->ttl ^ iph2->ttl) | - (iph->tos ^ iph2->tos) | - ((iph->frag_off ^ iph2->frag_off) & htons(IP_DF)); - - NAPI_GRO_CB(p)->flush |= flush; - - /* We need to store of the IP ID check to be included later - * when we can verify that this packet does in fact belong - * to a given flow. - */ - flush_id = (u16)(id - ntohs(iph2->id)); - - /* This bit of code makes it much easier for us to identify - * the cases where we are doing atomic vs non-atomic IP ID - * checks. Specifically an atomic check can return IP ID - * values 0 - 0xFFFF, while a non-atomic check can only - * return 0 or 0xFFFF. - */ - if (!NAPI_GRO_CB(p)->is_atomic || - !(iph->frag_off & htons(IP_DF))) { - flush_id ^= NAPI_GRO_CB(p)->count; - flush_id = flush_id ? 0xFFFF : 0; - } - - /* If the previous IP ID value was based on an atomic - * datagram we can overwrite the value and ignore it. - */ - if (NAPI_GRO_CB(skb)->is_atomic) - NAPI_GRO_CB(p)->flush_id = flush_id; - else - NAPI_GRO_CB(p)->flush_id |= flush_id; } - NAPI_GRO_CB(skb)->is_atomic = !!(iph->frag_off & htons(IP_DF)); NAPI_GRO_CB(skb)->flush |= flush; /* Note : No need to call skb_gro_postpull_rcsum() here, diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c index 7f045b881dd4..1b10ab3b0f6a 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c @@ -232,9 +232,7 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb) goto out_check_final; found: - /* Include the IP ID check below from the inner most IP hdr */ - flush = NAPI_GRO_CB(p)->flush; - flush |= (__force int)(flags & TCP_FLAG_CWR); + flush = (__force int)(flags & TCP_FLAG_CWR); flush |= (__force int)((flags ^ tcp_flag_word(th2)) & ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); flush |= (__force int)(th->ack_seq ^ th2->ack_seq); @@ -242,16 +240,7 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb) flush |= *(u32 *)((u8 *)th + i) ^ *(u32 *)((u8 *)th2 + i); - /* When we receive our second frame we can made a decision on if we - * continue this flow as an atomic flow with a fixed ID or if we use - * an incrementing ID. - */ - if (NAPI_GRO_CB(p)->flush_id != 1 || - NAPI_GRO_CB(p)->count != 1 || - !NAPI_GRO_CB(p)->is_atomic) - flush |= NAPI_GRO_CB(p)->flush_id; - else - NAPI_GRO_CB(p)->is_atomic = false; + flush |= gro_network_flush(th, th2, p, off); mss = skb_shinfo(p)->gso_size; diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index ad4c88fe7d15..c5a5155904cf 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -466,12 +466,12 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head, struct sk_buff *skb) { struct udphdr *uh = udp_gro_udphdr(skb); + int off = skb_gro_offset(skb); struct sk_buff *pp = NULL; struct udphdr *uh2; struct sk_buff *p; unsigned int ulen; int ret = 0; - int flush; /* requires non zero csum, for symmetry with GSO */ if (!uh->check) { @@ -529,17 +529,9 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head, skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); - flush = NAPI_GRO_CB(p)->flush; - - if (NAPI_GRO_CB(p)->flush_id != 1 || - NAPI_GRO_CB(p)->count != 1 || - !NAPI_GRO_CB(p)->is_atomic) - flush |= NAPI_GRO_CB(p)->flush_id; - else - NAPI_GRO_CB(p)->is_atomic = false; - - if (flush || skb_gro_receive(p, skb)) - ret = 1; + ret = gro_network_flush(uh, uh2, p, off); + if (!ret) + ret = skb_gro_receive(p, skb); } } diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c index ba41939537f2..c9a6bc1afc9a 100644 --- a/net/ipv6/ip6_offload.c +++ b/net/ipv6/ip6_offload.c @@ -288,19 +288,8 @@ INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head, nlen - sizeof(struct ipv6hdr))) goto not_same_flow; } - /* flush if Traffic Class fields are different */ - NAPI_GRO_CB(p)->flush |= !!((first_word & htonl(0x0FF00000)) | - (__force __be32)(iph->hop_limit ^ iph2->hop_limit)); - NAPI_GRO_CB(p)->flush |= flush; - - /* If the previous IP ID value was based on an atomic - * datagram we can overwrite the value and ignore it. - */ - if (NAPI_GRO_CB(skb)->is_atomic) - NAPI_GRO_CB(p)->flush_id = 0; } - NAPI_GRO_CB(skb)->is_atomic = true; NAPI_GRO_CB(skb)->flush |= flush; skb_gro_postpull_rcsum(skb, iph, nlen);