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| author | Florian Westphal <fw@strlen.de> | 2017-08-30 19:24:58 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-08-30 11:20:09 -0700 |
| commit | 31770e34e43d6c8dee129bfee77e56c34e61f0e5 (patch) | |
| tree | a4635a632732b39ef560a8f72eb3a81d04f01605 /include/linux/tcp.h | |
| parent | c1d2b4c3e204e602c97680335d082b8d012d08cd (diff) | |
| download | linux-31770e34e43d6c8dee129bfee77e56c34e61f0e5.tar.gz linux-31770e34e43d6c8dee129bfee77e56c34e61f0e5.tar.bz2 linux-31770e34e43d6c8dee129bfee77e56c34e61f0e5.zip | |
tcp: Revert "tcp: remove header prediction"
This reverts commit 45f119bf936b1f9f546a0b139c5b56f9bb2bdc78.
Eric Dumazet says:
We found at Google a significant regression caused by
45f119bf936b1f9f546a0b139c5b56f9bb2bdc78 tcp: remove header prediction
In typical RPC (TCP_RR), when a TCP socket receives data, we now call
tcp_ack() while we used to not call it.
This touches enough cache lines to cause a slowdown.
so problem does not seem to be HP removal itself but the tcp_ack()
call. Therefore, it might be possible to remove HP after all, provided
one finds a way to elide tcp_ack for most cases.
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/tcp.h')
| -rw-r--r-- | include/linux/tcp.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 267164a1d559..4aa40ef02d32 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -148,6 +148,12 @@ struct tcp_sock { u16 gso_segs; /* Max number of segs per GSO packet */ /* + * Header prediction flags + * 0x5?10 << 16 + snd_wnd in net byte order + */ + __be32 pred_flags; + +/* * RFC793 variables by their proper names. This means you can * read the code and the spec side by side (and laugh ...) * See RFC793 and RFC1122. The RFC writes these in capitals. |