2.4.x latency

Daniel Walton
2001-02-05T18:15:46Z

I'm experiencing an odd behavior under the 2.4.0 and 2.4.1 kernels on two
of my servers. I'm experiencing high latency periods. Sometimes the
periods are long and other times they are short. As a test I setup three
ping processes on one of the servers all pinging the same destination on
the LAN at the same time. Below is a sample of the ping output. The
strange thing is that while all three ping processes went through the
latency cycle, they each did it at different times. This tells me that
surely this isn't a network response issue or else all ping processes would
show the latency at the same time.

64 bytes from (216.185.106.18): icmp_seq=55 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=56 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=57 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=58 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=59 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=60 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=61 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=62 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=63 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=64 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=65 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=66 ttl=255 time=4121.7 ms
64 bytes from (216.185.106.18): icmp_seq=67 ttl=255 time=3259.0 ms
64 bytes from (216.185.106.18): icmp_seq=68 ttl=255 time=2384.6 ms
64 bytes from (216.185.106.18): icmp_seq=69 ttl=255 time=1511.2 ms
64 bytes from (216.185.106.18): icmp_seq=70 ttl=255 time=666.1 ms
64 bytes from (216.185.106.18): icmp_seq=71 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=72 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=73 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=74 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=75 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=76 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=77 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=78 ttl=255 time=0.1 ms
64 bytes from (216.185.106.18): icmp_seq=79 ttl=255 time=0.1 ms

The hardware in question are two Athlon servers with VIA KT133 chipset,
512Mb RAM, and IDE drives. One server uses the tulip network driver for a
Netgear FA-310. The other uses the NatSim DP83810 network driver for the
FA-312 and both exhibit the same problem. I've had 3com 3c900 series cards
in the machines as well and the problem still persisted.

One other interesting little fact is that if I ping the problem machines
from a good machine I always get 0.1 ms response times, even while the
pings from the problem machines are showing latency.

I hope this is enough information for someone to work with. I'm at a loss
for what the problem is and unfortunately I'm no kernel hacker. I
appreciate any help you guys can offer.

Thank you,
Daniel Walton