Date: Sat, 1 Dec 2001 13:21:05 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Richard Sharpe <sharpe@ns.aus.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Patch #2 (was Re: Found the problem, w/patch (was Re: FreeBSD performing worse than Linux?)) Message-ID: <200112012121.fB1LL5w36881@apollo.backplane.com> References: <20011128153817.T61580@monorchid.lemis.com> <15364.38174.938500.946169@caddis.yogotech.com> <20011128104629.A43642@walton.maths.tcd.ie> <5.1.0.14.1.20011130181236.00a80160@postamt1.charite.de> <200111302047.fAUKlT811090@apollo.backplane.com> <200111302130.fAULUU324648@apollo.backplane.com> <3C08CF9D.2030109@ns.aus.com>
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Richard (and others), please try this patch. With this patch I
get the following between two machines connected via a 100BaseTX
switch (full duplex):
----------------
test1:/home/dillon/dbench> ./tbench 1 test2
.1 clients started
..............+*
Throughput 6.13925 MB/sec (NB=7.67406 MB/sec 61.3925 MBit/sec) 1 procs
test1:/home/dillon/dbench> ./tbench 2 test2
..2 clients started
............................++**
Throughput 8.37795 MB/sec (NB=10.4724 MB/sec 83.7795 MBit/sec) 2 procs
----------------
On localhost I get:
----------------
test1:/home/dillon/dbench> ./tbench 1 localhost
.1 clients started
..............+*
Throughput 25.7156 MB/sec (NB=32.1445 MB/sec 257.156 MBit/sec) 1 procs
test1:/home/dillon/dbench> ./tbench 2 localhost
..2 clients started
............................++**
Throughput 36.5428 MB/sec (NB=45.6785 MB/sec 365.428 MBit/sec) 2 procs
test1:/home/dillon/dbench>
----------------
This is WITHOUT changing the default send and receive tcp buffers..
they're both 16384.
The bug I found is that when recv() is used with MSG_WAITALL,
which is what tbench does, soreceive() will block waiting for all
available input WITHOUT ever calling pr->pr_usrreqs->pru_rcvd(),
which means that if the sender filled up the receive buffer (16K default)
the receiver will never ack the 0 window... that is until the idle code
takes over after 5 seconds.
-Matt
Index: uipc_socket.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/uipc_socket.c,v
retrieving revision 1.68.2.16
diff -u -r1.68.2.16 uipc_socket.c
--- uipc_socket.c 2001/06/14 20:46:06 1.68.2.16
+++ uipc_socket.c 2001/12/01 21:09:13
@@ -910,6 +910,14 @@
!sosendallatonce(so) && !nextrecord) {
if (so->so_error || so->so_state & SS_CANTRCVMORE)
break;
+ /*
+ * The window might have closed to zero, make
+ * sure we send an ack now that we've drained
+ * the buffer or we might end up blocking until
+ * the idle takes over (5 seconds).
+ */
+ if (pr->pr_flags & PR_WANTRCVD && so->so_pcb)
+ (*pr->pr_usrreqs->pru_rcvd)(so, flags);
error = sbwait(&so->so_rcv);
if (error) {
sbunlock(&so->so_rcv);
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