diff options
| author | Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> | 2016-08-18 20:58:35 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-08-20 03:09:42 +0300 |
| commit | 4c2f2454964477c66ef57745daab203b71783f66 (patch) | |
| tree | 51f1daf90f01ee0775b82eab4727edbe36a80457 | |
| parent | 187335cdfec32475677b8ea2e7a165843fc38675 (diff) | |
| download | linux-4c2f2454964477c66ef57745daab203b71783f66.tar.xz | |
sctp: linearize early if it's not GSO
Because otherwise when crc computation is still needed it's way more
expensive than on a linear buffer to the point that it affects
performance.
It's so expensive that netperf test gives a perf output as below:
Overhead Command Shared Object Symbol
18,62% netserver [kernel.vmlinux] [k] crc32_generic_shift
2,57% netserver [kernel.vmlinux] [k] __pskb_pull_tail
1,94% netserver [kernel.vmlinux] [k] fib_table_lookup
1,90% netserver [kernel.vmlinux] [k] copy_user_enhanced_fast_string
1,66% swapper [kernel.vmlinux] [k] intel_idle
1,63% netserver [kernel.vmlinux] [k] _raw_spin_lock
1,59% netserver [sctp] [k] sctp_packet_transmit
1,55% netserver [kernel.vmlinux] [k] memcpy_erms
1,42% netserver [sctp] [k] sctp_rcv
# netperf -H 192.168.10.1 -l 10 -t SCTP_STREAM -cC -- -m 12000
SCTP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.10.1 () port 0 AF_INET
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB
212992 212992 12000 10.00 3016.42 2.88 3.78 1.874 2.462
After patch:
Overhead Command Shared Object Symbol
2,75% netserver [kernel.vmlinux] [k] memcpy_erms
2,63% netserver [kernel.vmlinux] [k] copy_user_enhanced_fast_string
2,39% netserver [kernel.vmlinux] [k] fib_table_lookup
2,04% netserver [kernel.vmlinux] [k] __pskb_pull_tail
1,91% netserver [kernel.vmlinux] [k] _raw_spin_lock
1,91% netserver [sctp] [k] sctp_packet_transmit
1,72% netserver [mlx4_en] [k] mlx4_en_process_rx_cq
1,68% netserver [sctp] [k] sctp_rcv
# netperf -H 192.168.10.1 -l 10 -t SCTP_STREAM -cC -- -m 12000
SCTP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.10.1 () port 0 AF_INET
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB
212992 212992 12000 10.00 3681.77 3.83 3.46 2.045 1.849
Fixes: 3acb50c18d8d ("sctp: delay as much as possible skb_linearize")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/sctp/input.c | 11 | ||||
| -rw-r--r-- | net/sctp/inqueue.c | 13 |
2 files changed, 7 insertions, 17 deletions
diff --git a/net/sctp/input.c b/net/sctp/input.c index c182db7d691f..69444d32ecda 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -119,7 +119,13 @@ int sctp_rcv(struct sk_buff *skb) skb_transport_offset(skb)) goto discard_it; - if (!pskb_may_pull(skb, sizeof(struct sctphdr))) + /* If the packet is fragmented and we need to do crc checking, + * it's better to just linearize it otherwise crc computing + * takes longer. + */ + if ((!(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) && + skb_linearize(skb)) || + !pskb_may_pull(skb, sizeof(struct sctphdr))) goto discard_it; /* Pull up the IP header. */ @@ -1177,9 +1183,6 @@ static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net, if ((skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) == SKB_GSO_SCTP) return NULL; - if (skb_linearize(skb)) - return NULL; - ch = (sctp_chunkhdr_t *) skb->data; /* The code below will attempt to walk the chunk and extract diff --git a/net/sctp/inqueue.c b/net/sctp/inqueue.c index c30ddb0f3190..6437aa97cfd7 100644 --- a/net/sctp/inqueue.c +++ b/net/sctp/inqueue.c @@ -170,19 +170,6 @@ next_chunk: chunk = list_entry(entry, struct sctp_chunk, list); - /* Linearize if it's not GSO */ - if ((skb_shinfo(chunk->skb)->gso_type & SKB_GSO_SCTP) != SKB_GSO_SCTP && - skb_is_nonlinear(chunk->skb)) { - if (skb_linearize(chunk->skb)) { - __SCTP_INC_STATS(dev_net(chunk->skb->dev), SCTP_MIB_IN_PKT_DISCARDS); - sctp_chunk_free(chunk); - goto next_chunk; - } - - /* Update sctp_hdr as it probably changed */ - chunk->sctp_hdr = sctp_hdr(chunk->skb); - } - if ((skb_shinfo(chunk->skb)->gso_type & SKB_GSO_SCTP) == SKB_GSO_SCTP) { /* GSO-marked skbs but without frags, handle * them normally |