Very busy netisr process

[Mohd Farouk Bin Baharim]

We have a K220 with 4 CPUs and there are 4 netisr processes (NETwork Interrupt Service Routine) and I understand that there is one per CPU.

3 of these netisr processes are using over 40% of the CPUs and other is using below 10%. That situation not for all operation day but sometime it's happen. We trying to find out what is causing them to have such a massive CPU usage.

We are running Ingres II with 300 PCs connecting into the Ingres database. If anyone know why it happen and has any suggestions to solve this ? I would be very happy to hear from you.

[Steve Steel]

Hi

I think this may not be unusual and is the result of getting unequal sharing of the CPU usage during hashing of the source IP and source port of the incoming frames!

If some connections stay open for a long time then other cpus will get more traffic


Steve STeel

[Tim Sanko]

One other thing for you to look at is the socket usage that tracks to the CPU getting 10% usage. If you have a sniffer, and a high number of sockes are in a wait state, then you may be seeing the reason for this activity. You can also see this with netstat -a.

What is your total CPU activity?

If it is not 85% or better accross all of the CPUs then I might treat this only as a curiosity.

Tim

[Brian Hackley]

Hello,

Your netisr usage is directly related to network traffic addressed to the HP, addressed to an IP broadcast or multicast address, or addressed to an Ethernet broadcast address. To find out what the network traffic is doing, your best bet is to collect packet capture for 2 or 3 minutes using a network sniffer/analyzer on the same network port(s).

Because of the CPU utilization, I would not suggest a host-based trace (e.g. nettl/netfmt, Ethereal, or tcpdump) because you will most likely drop many of the inbound packets. However if you do not have access to a sniffer, try one or more of those tools to collect a packet capture at the network card level (not at IP level since you probably are seeing other network types). Then you can format and analyze the packet capture file, or if you have a network admin, they can do this for you. This packet trace will help you to understand what network traffic is present, and the effects it is having on your HP-UX Server.

Hope that helps,

-> Brian Hackley