Hi David, Alan & tos group
I have just found linux-2.1.107 supports Sack.
I want to make some parameters more configurable and have added
MAX_WINDOW to the sysctl interface and have substituted MAX_WINDOW with
syctl_tcp_max_window.
Now I want to tune the send and receive sicket buffer size via sysctl.
I searched in the source code for the default settings for SO_SNDBUF and
SO_RCVBUF, but I could not find it. I only know, the buffer sizes are set
to 65535 Bytes. I know I can change it in my application via setsockbuf, but
I want to do it in the kernel.
Can you give me a tip to find the place to change at souce code ?
I have set the MAX_WINDOW in the tcp.h file to 262144 Bytes,
but it has no effect to throughput and the send / receive bufer size.
I have testet it with netperf from satla1 to satlab2:
satlab1 = satlab2 = linux-2.1.107 MAX_WINDOW= 262144
1. netperf -H satlab2 -l 60 -f k : default buffer sizes:
TCP STREAM TEST to satlab2
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^3bits/sec
65535 65535 65535 31.53 405.25
2. netperf -H satlab2 -l 60 -f k -- -s 262144 -S 262144
to force netperf to use 262144 Bytes for send and receive buffer size
TCP STREAM TEST to satlab2
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^3bits/sec
65535 65535 65535 31.42 407.33
Test from satlab1 to sun machine ( solaris 2.6 ..):
1. netperf -H satlab2 -l 60 -f k : default buffer sizes:
TCP STREAM TEST to sat
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^3bits/sec
262144 65535 65535 30.59 1304.39
2. netperf -H satlab2 -l 60 -f k -- -s 262144 -S 262144
TCP STREAM TEST to sat
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^3bits/sec
262640 65535 65535 30.62 1294.00
Does anybody know how to tune this tcp parameters ?
Thank you
Olaf
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