Bug 190176

Description of problem:

In the next discussion, all processes are single-thread.
Processes, which a very low priority (such renice 19 pid), continue to use one CPU (about 99%) even if 
normal priority process must run. The problem on 4 processor IA64 
In next example, the process 18011 (with low priority) must use only about few percent of the CPU but 
it takes 99%.

Is it a kernel problem or a nice command problem ?

We need to run low priority job for a long time. 
So when normal priority jobs are not running, these jobs must take 100% of each available CPU. 
But when normal priority jobs are running, these jobs must take about 5% or less of CPU if no cpu are 
available.

Do you have any solution ?






Version-Release number of selected component (if applicable):
kernel 2.6.9-5.EL


How reproducible:

Requires a SMP hardware.
Run two jobs with a low priority (with the renice command : renice 19 pid) 
Run three or more jobs with a normal priority.

Steps to Reproduce:
1.
2.
3.
  
Actual results:

top - 15:32:32 up 359 days,  3:40,  7 users,  load average: 5.93, 5.55, 5.74
Tasks: 132 total,   8 running, 123 sleeping,   0 stopped,   1 zombie
Cpu(s): 73.7% us,  0.1% sy, 26.2% ni,  0.0% id,  0.0% wa,  0.0% hi,  0.0% si
Mem:   4072640k total,  3842976k used,   229664k free,    89632k buffers
Swap:  4171744k total,   436144k used,  3735600k free,  3434944k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                             
30934 gastin    25   0  3552 2736  816 R 99.9  0.1   8:42.00 inpopx                                                              
18011 gastin    39  19  5584 4560 1072 R 99.8  0.1  34804:20 inpop                                                               
30996 gastin    25   0  3552 2720  800 R 95.2  0.1   1:23.63 inpopx                                                              
30911 manche    25   0 13792 6256 2208 R 57.0  0.2   9:04.15 inpop                                                               
30913 manche    25   0 13792 6256 2208 R 42.6  0.2   9:08.59 inpop                                                               
25591 gastin    39  19  5584 4560 1072 R  4.8  0.1  26658:37 inpop                                                               

Expected results:


Additional info: