[CentOS] UDP Perfomance tuning

Hi,

We are running on 5.5 on a HP ProLiant DL360 G6.
Kernel version is 2.6.18-194.17.1.el5 (we had also tested with the latest
available kernel kernel-2.6.18-238.1.1.el5.x86_64)

We running some performance tests using the "iperf" utility.

We are seeing very bad and inconsistent performance on the UDP testing.

The maximum we could get, was 440 Mbits/sec, and it varies from 250 to 440
Mbits/sec.
We are connected on a 1000Mb/s link, we also tested the same using a
cross-over connections between the two machines, but the same performance.

We also see a lot of dropped UDP packets.

Udp:
    551522838 packets received
    1902 packets to unknown port received.
    109709802 packet receive errors
    7239 packets sent


We had checked all the kernel configurations and set them as recommended.

This is the settings and tests we have done

Server:
net.core.rmem_default = 2097152
net.core.wmem_default = 2097152
net.core.rmem_max = 8388608
net.core.wmem_max = 8388608
strace -fttt -o /tmp/server.trace iperf -s -u -p 2222 -w 6m -i 5 -l 1k

Client:
net.core.rmem_default = 2097152
net.core.wmem_default = 2097152
net.core.rmem_max = 8388608
net.core.wmem_max = 8388608
strace -fttt -o /tmp/client.trace iperf -p 2222 -u -w 6m -i 5 -t 60 -c
192.168.1.2 -b 990M -l 1k

Can someone please help me with this, since I am running in circles and
can't get the required UDP performance?

-- 
Prasad Pillarisetti
"If everything is coming your way, then you are in the wrong lane"
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