> From fafe76713523c8e9767805cfdc7b73323d7bf180 Mon Sep 17 00:00:00 2001

quoted text
> From: Willy Tarreau

> Date: Thu, 8 Jan 2009 17:10:13 +0100

> Subject: [PATCH] tcp: splice as many packets as possible at once

>

> Currently, in non-blocking mode, tcp_splice_read() returns after

> splicing one segment regardless of the len argument. This results

> in low performance and very high overhead due to syscall rate when

> splicing from interfaces which do not support LRO.

>

> The fix simply consists in not breaking out of the loop after the

> first read. That way, we can read up to the size requested by the

> caller and still return when there is no data left.

>

> Performance has significantly improved with this fix, with the

> number of calls to splice() divided by about 20, and CPU usage

> dropped from 100% to 75%.

> 

I get similar results with my testing here. Benchmarking an application

with this patch shows that more than one packet is being splice()d in at

once, as a result I see a doubling in throughput.
Tested-by: Ben Mansell 
> Signed-off-by: Willy Tarreau

quoted text
> ---

>  net/ipv4/tcp.c |    2 +-

>  1 files changed, 1 insertions(+), 1 deletions(-)

>

> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c

> index 35bcddf..80261b4 100644

> --- a/net/ipv4/tcp.c

> +++ b/net/ipv4/tcp.c

> @@ -615,7 +615,7 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,

>  		lock_sock(sk);

>

>  		if (sk->sk_err || sk->sk_state == TCP_CLOSE ||

> -		    (sk->sk_shutdown & RCV_SHUTDOWN) || !timeo ||

> +		    (sk->sk_shutdown & RCV_SHUTDOWN) ||

>  		    signal_pending(current))

>  			break;

>  	}

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