Messages in this thread Patch in this message | | | Date | Thu, 8 Jan 2009 18:30:28 +0100 | From | Willy Tarreau <> | Subject | [PATCH] tcp: splice as many packets as possible at once |
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Jens,
here's the other patch I was talking about, for better behaviour of non-blocking splice(). Ben Mansell also confirms similar improvements in his tests, where non-blocking splice() initially showed half of read()/write() performance. Ben, would you mind adding a Tested-By line ?
Also, please note that this is unrelated to the corruption bug I reported and does not fix it.
Regards, Willy
From fafe76713523c8e9767805cfdc7b73323d7bf180 Mon Sep 17 00:00:00 2001 From: Willy Tarreau <w@1wt.eu> 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%.
Signed-off-by: Willy Tarreau <w@1wt.eu> --- 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; } -- 1.6.0.3
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