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Commit e9df7d7f authored by Benjamin LaHaise's avatar Benjamin LaHaise Committed by David S. Miller
Browse files

[AF_UNIX]: use shift instead of integer division 



The patch below replaces a divide by 2 with a shift -- sk_sndbuf is an
integer, so gcc emits an idiv, which takes 10x longer than a shift by 1.
This improves af_unix bandwidth by ~6-10K/s.  Also, tidy up the comment
to fit in 80 columns while we're at it.

Signed-off-by: default avatarBenjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 231d06ae

net/unix/af_unix.c

+5 −5
Original line number Diff line number Diff line
@@ -1427,15 +1427,15 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock, 
	while(sent < len)

	{

		/*

		 *	Optimisation for the fact that under 0.01% of X messages typically

		 *	need breaking up.

		 *	Optimisation for the fact that under 0.01% of X

		 *	messages typically need breaking up.

		 */



		size = len-sent;



		/* Keep two messages in the pipe so it schedules better */

		if (size > sk->sk_sndbuf / 2 - 64)

			size = sk->sk_sndbuf / 2 - 64;

		if (size > ((sk->sk_sndbuf >> 1) - 64))

			size = (sk->sk_sndbuf >> 1) - 64;



		if (size > SKB_MAX_ALLOC)

			size = SKB_MAX_ALLOC;