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  1. 12 11月, 2014 1 次提交
    • E
      tcp: move sk_mark_napi_id() at the right place · 3d97379a
      由 Eric Dumazet 提交于 
      sk_mark_napi_id() is used to record for a flow napi id of incoming
packets for busypoll sake.
We should do this only on established flows, not on listeners.

This was 'working' by virtue of the socket cloning, but doing
this on SYN packets in unecessary cache line dirtying.

Even if we move sk_napi_id in the same cache line than sk_lock,
we are working to make SYN processing lockless, so it is desirable
to set sk_napi_id only for established flows.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      3d97379a
  3. 11 11月, 2014 3 次提交
    • H
      ipv4: Avoid reading user iov twice after raw_probe_proto_opt · c008ba5b
      由 Herbert Xu 提交于 
      Ever since raw_probe_proto_opt was added it had the problem of
causing the user iov to be read twice, once during the probe for
the protocol header and once again in ip_append_data.

This is a potential security problem since it means that whatever
we're probing may be invalid.  This patch plugs the hole by
firstly advancing the iov so we don't read the same spot again,
and secondly saving what we read the first time around for use
by ip_append_data.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c008ba5b
    • H
      ipv4: Use standard iovec primitive in raw_probe_proto_opt · 32b5913a
      由 Herbert Xu 提交于 
      The function raw_probe_proto_opt tries to extract the first two
bytes from the user input in order to seed the IPsec lookup for
ICMP packets.  In doing so it's processing iovec by hand and
overcomplicating things.

This patch replaces the manual iovec processing with a call to
memcpy_fromiovecend.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      32b5913a
    • E
      net: gro: add a per device gro flush timer · 3b47d303
      由 Eric Dumazet 提交于 
      Tuning coalescing parameters on NIC can be really hard.

Servers can handle both bulk and RPC like traffic, with conflicting
goals : bulk flows want as big GRO packets as possible, RPC want minimal
latencies.

To reach big GRO packets on 10Gbe NIC, one can use :

ethtool -C eth0 rx-usecs 4 rx-frames 44

But this penalizes rpc sessions, with an increase of latencies, up to
50% in some cases, as NICs generally do not force an interrupt when
a packet with TCP Push flag is received.

Some NICs do not have an absolute timer, only a timer rearmed for every
incoming packet.

This patch uses a different strategy : Let GRO stack decides what do do,
based on traffic pattern.

Packets with Push flag wont be delayed.
Packets without Push flag might be held in GRO engine, if we keep
receiving data.

This new mechanism is off by default, and shall be enabled by setting
/sys/class/net/ethX/gro_flush_timeout to a value in nanosecond.

To fully enable this mechanism, drivers should use napi_complete_done()
instead of napi_complete().

Tested:
 Ran 200 netperf TCP_STREAM from A to B (10Gbe mlx4 link, 8 RX queues)

Without this feature, we send back about 305,000 ACK per second.

GRO aggregation ratio is low (811/305 = 2.65 segments per GRO packet)

Setting a timer of 2000 nsec is enough to increase GRO packet sizes
and reduce number of ACK packets. (811/19.2 = 42)

Receiver performs less calls to upper stacks, less wakes up.
This also reduces cpu usage on the sender, as it receives less ACK
packets.

Note that reducing number of wakes up increases cpu efficiency, but can
decrease QPS, as applications wont have the chance to warmup cpu caches
doing a partial read of RPC requests/answers if they fit in one skb.

B:~# sar -n DEV 1 10 | grep eth0 | tail -1
Average:         eth0 811269.80 305732.30 1199462.57  19705.72      0.00
0.00      0.50

B:~# echo 2000 >/sys/class/net/eth0/gro_flush_timeout

B:~# sar -n DEV 1 10 | grep eth0 | tail -1
Average:         eth0 811577.30  19230.80 1199916.51   1239.80      0.00
0.00      0.50
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      3b47d303
  5. 09 11月, 2014 1 次提交
  7. 08 11月, 2014 3 次提交
  9. 07 11月, 2014 6 次提交
  11. 06 11月, 2014 26 次提交