Commit 9bacd256 authored Apr 17, 2020 by Eric Dumazet Committed by David S. Miller Apr 18, 2020

tcp: cache line align MAX_TCP_HEADER



TCP stack is dumb in how it cooks its output packets.

Depending on MAX_HEADER value, we might chose a bad ending point
for the headers.

If we align the end of TCP headers to cache line boundary, we
make sure to always use the smallest number of cache lines,
which always help.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 56e639e6

include/net/tcp.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -51,7 +51,7 @@ extern struct inet_hashinfo tcp_hashinfo;
		extern struct percpu_counter tcp_orphan_count;
		void tcp_time_wait(struct sock *sk, int state, int timeo);

		#define MAX_TCP_HEADER (128 + MAX_HEADER)
		#define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER)
		#define MAX_TCP_OPTION_SPACE 40
		#define TCP_MIN_SND_MSS 48
		#define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)

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