{inet,ipv6}_gro_receive functions perform flush checks (ttl, flags, iph->id, ...) against all packets in a loop. These flush checks are used currently only in tcp flows in GRO.
These checks need to be done only once in tcp_gro_receive and only against the found p skb, since they only affect flush and not same_flow.
Levaraging 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. 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.
For example, running 40 IP/UDP netperf connections: ./super_netperf.sh 40 -H 1.1.1.2 -t UDP_STREAM -l 120
Running perf top for 90s we can see that relatively less time is spent on inet_gro_receive when GRO is not coalescing UDP:
net-next: 1.26% [kernel] [k] inet_gro_receive
patch applied: 0.85% [kernel] [k] inet_gro_receive
udpgro_bench.sh single connection GRO improvement: net-next: 0.76% [kernel] [k] inet_gro_receive
patch applied: 0.61% [kernel] [k] inet_gro_receive
Signed-off-by: Richard Gobert richardbgobert@gmail.com --- include/net/gro.h | 9 ++---- net/core/gro.c | 3 -- net/ipv4/af_inet.c | 36 --------------------- net/ipv4/tcp_offload.c | 72 ++++++++++++++++++++++++++++++++++-------- net/ipv6/ip6_offload.c | 11 ------- 5 files changed, 62 insertions(+), 69 deletions(-)
diff --git a/include/net/gro.h b/include/net/gro.h index a1cc8e8c2ebd..73e266194528 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 { diff --git a/net/core/gro.c b/net/core/gro.c index 7c468ed805f4..f8cbc08197f7 100644 --- a/net/core/gro.c +++ b/net/core/gro.c @@ -329,8 +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; @@ -470,7 +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..9d7fd79ee915 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1513,7 +1513,6 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb)
list_for_each_entry(p, head, list) { struct iphdr *iph2; - u16 flush_id;
if (!NAPI_GRO_CB(p)->same_flow) continue; @@ -1530,43 +1529,8 @@ 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 a63af9a6b0f7..ed9947bb903d 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c @@ -178,6 +178,55 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, return segs; }
+static int inet_gro_flush(const struct iphdr *iph, const struct iphdr *iph2, + struct sk_buff *p, u32 outer) +{ + const u32 id = ntohl(*(__be32 *)&iph->id); + const u32 id2 = ntohl(*(__be32 *)&iph2->id); + const int flush_id = ntohs(id >> 16) - ntohs(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)); + + /* 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. + */ + if (count == 1) { + is_atomic = df && flush_id == 0; + NAPI_GRO_CB(p)->is_atomic = is_atomic; + } else { + is_atomic = df && NAPI_GRO_CB(p)->is_atomic; + } + + /* Ignore outer IP ID value if based on atomic datagram. */ + outer = (outer && df) - 1; + is_atomic--; + + return flush | ((flush_id ^ (count & is_atomic)) & outer); +} + +static int ipv6_gro_flush(const struct ipv6hdr *iph, const struct ipv6hdr *iph2) +{ + /* Version:4<Traffic_Class:8><Flow_Label:20> */ + __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 int gro_network_flush(const void *nh, const void *nh2, + struct sk_buff *p, u32 outer) +{ + return (((struct iphdr *)nh)->version == 6) ? ipv6_gro_flush(nh, nh2) : + inet_gro_flush(nh, nh2, p, outer); +} + struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb) { struct sk_buff *pp = NULL; @@ -190,6 +239,7 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb) unsigned int mss = 1; unsigned int hlen; unsigned int off; + bool encap_mark; int flush = 1; int i;
@@ -232,9 +282,7 @@ 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 +290,14 @@ 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; + encap_mark = NAPI_GRO_CB(skb)->encap_mark; + for (i = 0; i <= encap_mark; i++) { + const u16 diff = off - NAPI_GRO_CB(skb)->network_offsets[i]; + + flush |= gro_network_flush((void *)th - diff, + (void *)th2 - diff, + p, i != encap_mark); + }
mss = skb_shinfo(p)->gso_size;
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);