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author | Eric Dumazet <edumazet@google.com> | 2012-04-22 23:38:54 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2012-04-23 22:28:28 -0400 |
commit | da882c1f2ecadb0ed582628ec1585e36b137c0f0 (patch) | |
tree | c89b136ec4ae978adf1078fdce199423a59ba8c0 /include/net/xfrm.h | |
parent | f545a38f74584cc7424cb74f792a00c6d2589485 (diff) | |
download | linux-da882c1f2ecadb0ed582628ec1585e36b137c0f0.tar.gz linux-da882c1f2ecadb0ed582628ec1585e36b137c0f0.tar.bz2 linux-da882c1f2ecadb0ed582628ec1585e36b137c0f0.zip |
tcp: sk_add_backlog() is too agressive for TCP
While investigating TCP performance problems on 10Gb+ links, we found a
tcp sender was dropping lot of incoming ACKS because of sk_rcvbuf limit
in sk_add_backlog(), especially if receiver doesnt use GRO/LRO and sends
one ACK every two MSS segments.
A sender usually tweaks sk_sndbuf, but sk_rcvbuf stays at its default
value (87380), allowing a too small backlog.
A TCP ACK, even being small, can consume nearly same truesize space than
outgoing packets. Using sk_rcvbuf + sk_sndbuf as a limit makes sense and
is fast to compute.
Performance results on netperf, single flow, receiver with disabled
GRO/LRO : 7500 Mbits instead of 6050 Mbits, no more TCPBacklogDrop
increments at sender.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/xfrm.h')
0 files changed, 0 insertions, 0 deletions