[AF_UNIX]: use shift instead of integer division (e9df7d7f) · Commits · 戴 / test

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:

Benjamin LaHaise <benjamin.c.lahaise@intel.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

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;

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