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Help! What is the daemon named "netisr"?Which eat so much CPU?

leereg_4
Advisor

Help! What is the daemon named "netisr"?Which eat so much CPU?

Load averages: 17.83, 13.92, 11.56
1074 processes: 1072 sleeping, 2 running
Cpu states:
CPU LOAD USER NICE SYS IDLE BLOCK SWAIT INTR SSYS
0 15.81 3.5% 0.0% 31.4% 65.1% 0.0% 0.0% 0.0% 0.0%
1 19.85 7.5% 0.0% 39.5% 53.0% 0.0% 0.0% 0.0% 0.0%
--- ---- - - - - - - - -----
avg 17.83 5.4% 0.0% 35.5% 59.2% 0.0% 0.0% 0.0% 0.0%

Memory: 730472K (372100K) real, 850024K (359740K) virtual, 19784K free Page# 1/
98

CPU TTY PID USERNAME PRI NI SIZE RES STATE TIME %WCPU %CPU COMMAND
1 rroot 20 root 100 20 0K 0K sleep 1213:27 5.81 5.80 netisr
Always UNIX
3 REPLIES
Alex Glennie
Honored Contributor

Re: Help! What is the daemon named "netisr"?Which eat so much CPU?

High netisr is symptomatic of a problem somewhere else, ie on the network, in
the TCP/IP stack, the application, or with disk access. On a busy system,
netisr of 80% is quite acceptable, but it is usually a good idea to start
looking for bottlenecks if netisr goes above 30%. A brief explanation of
netisr follows:

"Whenever a network packet arrives the lan card sends an interrupt to
it's CPU. The interrupt routine checks if the packet is valid and
puts it onto the ip_intrqueue. The last thing the interrupt routine
does is to wakeup the netisr to process the packet. If you have a lot
of loopback traffic, all netisr are woken up to process the packets.
The netisr finishes work, when no packet is left on the ip_intrqueue."

To clear netisr down, reboot the system, but you will probably only remove the
symptom and not the problem. A better way is to stop the running applications
one at a time until netisr starts to drop again. A high level of loopback
traffic in netstat -rn usually indicates an application or routing issue.
leereg_4
Advisor

Re: Help! What is the daemon named "netisr"?Which eat so much CPU?

# netstat -rn
Routing tables
Destination Gateway Flags Refs Use Interface Pmtu PmtuTime
127.0.0.1 127.0.0.1 UH 8 103260 lo0 4608
x.x.x.x 127.0.0.1 UH 3893912339 lo0 4608
default x.x.x.x UG 3 1897251 lan0 1500
x.x.x.x x.x.x.x U 461872090862 lan0 1500
Always UNIX
Magdi KAMAL
Respected Contributor