Re: Network slowdown due to CFS

On Wed, 2007-09-26 at 10:52 +0200, Martin Michlmayr wrote:
I noticed that my network performance has gone down from 2.6.22
from [ 3] 0.0-10.0 sec 113 MBytes 95.0 Mbits/sec
to [ 3] 0.0-10.0 sec 75.7 MBytes 63.3 Mbits/sec
with 2.6.23-rc1 (and 2.6.23-rc8), as measured with iperf.

FWIW, on my box blasting localhost, I see the opposite, repeatably.

root@Homer: iperf -v
iperf version 2.0.2 (03 May 2005) pthreads

2.6.22.1-smp
for i in `seq 1 3`; do iperf -c localhost; done >> /xx

------------------------------------------------------------
Client connecting to localhost, TCP port 5001
TCP window size: 49.2 KByte (default)
------------------------------------------------------------
[ 3] local 127.0.0.1 port 21383 connected with 127.0.0.1 port 5001
[ 3] 0.0-10.1 sec 518 MBytes 432 Mbits/sec
------------------------------------------------------------
Client connecting to localhost, TCP port 5001
TCP window size: 49.2 KByte (default)
------------------------------------------------------------
[ 3] local 127.0.0.1 port 21384 connected with 127.0.0.1 port 5001
[ 3] 0.0-10.0 sec 325 MBytes 273 Mbits/sec
------------------------------------------------------------
Client connecting to localhost, TCP port 5001
TCP window size: 49.2 KByte (default)
------------------------------------------------------------
[ 3] local 127.0.0.1 port 21385 connected with 127.0.0.1 port 5001
[ 3] 0.0-10.0 sec 434 MBytes 363 Mbits/sec

2.6.23-rc8-smp-d
for i in `seq 1 3`; do iperf -c localhost; done >> /xx

------------------------------------------------------------
Client connecting to localhost, TCP port 5001
TCP window size: 49.2 KByte (default)
------------------------------------------------------------
[ 3] local 127.0.0.1 port 11650 connected with 127.0.0.1 port 5001
[ 3] 0.0-10.0 sec 2.01 GBytes 1.72 Gbits/sec
------------------------------------------------------------
Client connecting to localhost, TCP port 5001
TCP window size: 49.2 KByte (default)
------------------------------------------------------------
[ 3] local 127.0.0.1 port 11651 connected with 127.0.0.1 port 5001
[ 3] 0.0-10.0 sec 2.02 GBytes 1.74 Gbits/sec
------------------------------------------------------------
Client connecting to localhost, TCP port 5001
TCP window size: 49.2 KByte (default)
------------------------------------------------------------
[ 3] local 127.0.0.1 port 11652 connected with 127.0.0.1 port 5001
[ 3] 0.0-10.0 sec 2.10 GBytes 1.81 Gbits/sec


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