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| author | Eric Dumazet <edumazet@google.com> | 2013-05-15 19:25:55 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-05-16 15:19:45 -0700 |
| commit | d2cf43674e17ca1c16c68d46d987d2f17bf7c371 (patch) | |
| tree | f308a56b13f27297349f44f785f3c5d0d651ac07 /net/ipv4/tcp_input.c | |
| parent | dbbffe6898fd0d7bac66ded5d3c58835b13ddefc (diff) | |
| download | blackbird-op-linux-d2cf43674e17ca1c16c68d46d987d2f17bf7c371.tar.gz blackbird-op-linux-d2cf43674e17ca1c16c68d46d987d2f17bf7c371.zip | |
tcp: speedup tcp_fixup_rcvbuf()
tcp_fixup_rcvbuf() contains a loop to estimate initial socket
rcv space needed for a given mss. With large MTU (like 64K on lo),
we can loop ~500 times and consume a lot of cpu cycles.
perf top of 200 concurrent netperf -t TCP_CRR
5.62% netperf [kernel.kallsyms] [k] tcp_init_buffer_space
1.71% netperf [kernel.kallsyms] [k] _raw_spin_lock
1.55% netperf [kernel.kallsyms] [k] kmem_cache_free
1.51% netperf [kernel.kallsyms] [k] tcp_transmit_skb
1.50% netperf [kernel.kallsyms] [k] tcp_ack
Lets use a 100% factor, and remove the loop.
100% is needed anyway for tcp_adv_win_scale=1
default value, and is also the maximum factor.
Refs: commit b49960a05e32
("tcp: change tcp_adv_win_scale and tcp_rmem[2]")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 08bbe6096528..b358e8c98607 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -360,9 +360,7 @@ static void tcp_fixup_rcvbuf(struct sock *sk) if (mss > 1460) icwnd = max_t(u32, (1460 * TCP_DEFAULT_INIT_RCVWND) / mss, 2); - rcvmem = SKB_TRUESIZE(mss + MAX_TCP_HEADER); - while (tcp_win_from_space(rcvmem) < mss) - rcvmem += 128; + rcvmem = 2 * SKB_TRUESIZE(mss + MAX_TCP_HEADER); rcvmem *= icwnd; |
