Hi guys,

thank you for reading this thread.

i am totally a newbie in Linux and need some help regarding CPU Usage on my IBM P520 with 8 cores installed, 8Gig RAM.

the problem is that the CPU occupied for a process is always limitted to 99.9% shown in 'top' as follow: (i tried on 2 different box and found the same problem, which i believe and hope it would go faster)

top - 20:45:25 up 587 days, 2:01, 3 users, load average: 26.72, 23.61, 22.10
Tasks: 142 total, 2 running, 140 sleeping, 0 stopped, 0 zombie
Cpu(s): 52.0% us, 47.5% sy, 0.1% ni, 0.1% id, 0.0% wa, 0.1% hi, 0.2% si
Mem: 7791156k total, 6844564k used, 946592k free, 13512k buffers
Swap: 8385848k total, 1831556k used, 6554292k free, 417520k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
8365 root 16 0 844m 238m 10m S 99.9 3.1 2732:40 javaserver
10379 root 16 0 646m 27m 4888 S 0.7 0.4 307:48.89 javanoti
13050 root 15 0 2194m 398m 10m S 0.7 5.2 47:13.54 javamwimca_mala

-----------------------------------------------------------------------------------------

top - 20:46:54 up 137 days, 7:34, 2 users, load average: 2.98, 3.34, 3.51
Tasks: 187 total, 1 running, 186 sleeping, 0 stopped, 0 zombie
Cpu(s): 9.2% us, 0.7% sy, 0.0% ni, 87.9% id, 1.6% wa, 0.1% hi, 0.5% si
Mem: 7790880k total, 7782072k used, 8808k free, 50024k buffers
Swap: 8385848k total, 264k used, 8385584k free, 6870568k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
23314 mysql 16 0 706m 559m 5460 S 99.9 7.4 2306:11 mysqld
6261 root 15 0 0 0 0 S 1.9 0.0 84:27.40 kjournald
26478 root 15 0 2424 988 724 R 1.9 0.0 0:00.02 top

the redhat version i currently use is :

Red Hat Enterprise Linux AS release 4 (Nahant Update 3)
Linux APP2 2.6.9-34.EL #1 SMP Fri Feb 24 16:46:57 EST 2006 ppc64 ppc64 ppc64 GNU/Linux

very much appreciated for the help and advice.

thanks.

That's not a problem, just basic physics - a single process can only run on 1 CPU, and by definition 100% is all there is.
Multi-threaded applications can take advantage of extra processors (CPUs), but not single threaded apps.

For comparison, i also have another linux box using dual Intel Quad Core and also runs mysql, but it can reach to 175% CPU usage shown in 'top'.

i need this POWER box to do the same for my applications.

in addition,

MySql is multi threaded application. and lookin deeper into the top, the cpu time is distributed through the cores..

top - 05:28:44 up 25 days, 18:33, 2 users, load average: 0.90, 1.06, 1.20
Tasks: 701 total, 1 running, 700 sleeping, 0 stopped, 0 zombie
Cpu0 : 14.1% us, 2.0% sy, 0.0% ni, 83.6% id, 0.3% wa, 0.0% hi, 0.0% si
Cpu1 : 10.2% us, 2.3% sy, 0.0% ni, 87.5% id, 0.0% wa, 0.0% hi, 0.0% si
Cpu2 : 7.5% us, 1.0% sy, 0.0% ni, 88.6% id, 2.3% wa, 0.3% hi, 0.3% si
Cpu3 : 11.1% us, 2.0% sy, 0.0% ni, 86.3% id, 0.3% wa, 0.3% hi, 0.0% si
Cpu4 : 10.8% us, 1.0% sy, 0.0% ni, 86.2% id, 1.6% wa, 0.3% hi, 0.0% si
Cpu5 : 8.9% us, 4.3% sy, 0.0% ni, 86.5% id, 0.3% wa, 0.0% hi, 0.0% si
Cpu6 : 17.5% us, 2.0% sy, 0.0% ni, 80.2% id, 0.3% wa, 0.0% hi, 0.0% si
Cpu7 : 4.6% us, 2.6% sy, 0.0% ni, 92.2% id, 0.3% wa, 0.0% hi, 0.3% si
Mem: 7823024k total, 7809488k used, 13536k free, 64264k buffers
Swap: 8388472k total, 192k used, 8388280k free, 6749000k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
6208 mysql 15 0 746m 534m 5348 S 96.5 7.0 41196:07 mysqld
21408 root 16 0 2696 1380 788 S 1.3 0.0 3:38.21 top
26270 root 16 0 2700 1384 788 R 1.3 0.0 0:00.55 top

Then you've hit the limit of that process.
Might be busy, might be something specific to the architecture change (PPC vs. Intel), might be a bug. First place to look would be the MySql options and ensure they are appropriate for the PPC environment.
No suggestions as I don't use either.