Re: [PATCH v2 net-next] tcp: TSO packets automatic sizing
From: Eric Dumazet <hidden>
Date: 2013-08-26 20:28:13
On Mon, 2013-08-26 at 12:09 -0700, Yuchung Cheng wrote:
init write of 10MSS now looks good, but the delay still shows up if 9
< write-size < 10 MSS...
I use packetdrill to do write(14599) bytes of MSS 1460
0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
0.000 bind(3, ..., ...) = 0
0.000 listen(3, 1) = 0
0.100 < S 299245565:299245565(0) win 32792 <mss
1460,sackOK,nop,nop,nop,wscale 7>
0.100 > S. 0:0(0) ack 299245566 <mss 1460,nop,nop,sackOK,nop,wscale 6>
0.200 < . 1:1(0) ack 1 win 257
0.200 accept(3, ..., ...) = 4
+.000 write(4, ..., 13141) = 13141
+3 %{ print "done" }%
and tcpdump shows
31.819958 IP cli > srv: S 299245565:299245565(0) win 32792 <mss 1460,sackOK,nop,
nop,nop,wscale 7>
000034 IP srv > cli: S 203810874:203810874(0) ack 299245566 win 29200
<mss 1460,nop,nop,sackOK,nop,wscale 6>
099966 IP cli > srv: . ack 1 win 257
000079 IP srv > cli: . 1:2921(2920) ack 1 win 457
000010 IP srv > cli: . 2921:5841(2920) ack 1 win 457
000005 IP srv > cli: . 5841:8761(2920) ack 1 win 457
000004 IP srv > cli: . 8761:11681(2920) ack 1 win 457
199659 IP srv > cli: . 11681:13141(1460) ack 1 win 457
...It works correctly here, I wonder what's happening on your host. lpq83:~# tcpdump -p -n -s 0 -i any port 8080 -ttt tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on any, link-type LINUX_SLL (Linux cooked), capture size 65535 bytes 000000 IP 192.0.2.1.42148 > 192.168.0.1.8080: S 299245565:299245565(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7> 000042 IP 192.168.0.1.8080 > 192.0.2.1.42148: S 223873324:223873324(0) ack 299245566 win 29200 <mss 1460,nop,nop,sackOK,nop,wscale 6> 099946 IP 192.0.2.1.42148 > 192.168.0.1.8080: . ack 1 win 257 000087 IP 192.168.0.1.8080 > 192.0.2.1.42148: . 1:2921(2920) ack 1 win 457 000006 IP 192.168.0.1.8080 > 192.0.2.1.42148: . 2921:5841(2920) ack 1 win 457 000004 IP 192.168.0.1.8080 > 192.0.2.1.42148: . 5841:8761(2920) ack 1 win 457 000004 IP 192.168.0.1.8080 > 192.0.2.1.42148: . 8761:11681(2920) ack 1 win 457 000005 IP 192.168.0.1.8080 > 192.0.2.1.42148: . 11681:13141(1460) ack 1 win 457 000002 IP 192.168.0.1.8080 > 192.0.2.1.42148: P 13141:13142(1) ack 1 win 457