Red Hat Bugzilla – Bug 107339
top shows 0% CPU usage for niced processes
Last modified: 2007-11-30 17:06:58 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030701 Description of problem: "top" incorrectly shows 0% CPU usage for "nice"ed processes. vmstat shows correct cpu usage, "top" "CPU states" display shows correct cpu usage. Version-Release number of selected component (if applicable): procps-2.0.13-9E How reproducible: Always Steps to Reproduce: 1. run "nice -10 ./eatcpu.exe" (see source code below) 2. run "top" 3. observe high cpu usage in the "cpu nice" state display 4. observe high load average 5. observe "eatcpu.exe" incorrectly showing 0% cpu usage in the per-process display Additional info: Source code for eatcpu.exe: [olchansk@tw00 utils]$ cat ./eatcpu.c /* eatcpu.c */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> int main(int argc,char*argv[]) { while (1) { /* do nothing */ } /* NOT REACHED */ } /* end file */ [olchansk@tw00 utils]$ g++ -o eatcpu.exe -g -O0 eatcpu.c [olchansk@tw00 utils]$ nice -10 ./eatcpu.exe K.O.
Forgot to attach the incorrect "top" output while running "nice -10 ./eatcpu.exe": 19:40:24 up 8 days, 5:17, 4 users, load average: 1.04, 0.41, 0.25 75 processes: 73 sleeping, 2 running, 0 zombie, 0 stopped CPU states: cpu user nice system irq softirq iowait idle total 0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 100.0% cpu00 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% cpu01 0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% Mem: 2037152k av, 1632696k used, 404456k free, 0k shrd, 230768k buff 434500k actv, 65012k in_d, 35684k in_c Swap: 4096564k av, 16k used, 4096548k free 664644k cached PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND 1466 olchansk 15 0 1336 1336 948 R 0.0 0.0 0:00 0 top 1495 olchansk 35 10 768 768 664 R N 0.0 0.0 0:00 1 eatcpu.exe K.O.
ugh. pretty bad.
Hmm, arjan claimed he has seen similar bugs that have been fixes in later kernel versions. Might be fixed already.
Yeah. I don't get this with kernel 2.4.21-2.ELsmp and procps-2.0.13-9.2E. What kernel are you using? Can you try a later one?
Too many different versions floating around. I have kernel 2.4.21-1.1931.2.393.entsmp and procps-2.0.13-9E. Where do I get the rpms you guys mention? Amd64 Rawhide has procps-2.0.17-1. I installed it and it has the same problem. Amd64 Rawhide has kernel-2.4.20-9.2, older than the one you mention (2.4.21-2.ELsmp) and older than what I run (2.4.21-1.1931.2.393.entsmp). Should I try it? BTW, I am confused by the "taroon" versions. What came with the machine claims to be "Red Hat Enterprise Linux release 2.9.5WS (Taroon)". Is this "beta", "beta2" or what? K.O.
I'm really not sure about the kernel versions. I'm reassigning to kernel so someone who knows about this can reply.
this was fixed in kernel, latest is in RHN
I confirm that the problem does not exist with kernel-smp-2.4.21-4.EL (from RHEL3.0) and procps-2.0.17-1 (from Rawhide). K.O.