Process & threads - Karmic vs past kernels

[Peter Matulis]

Chase Douglas wrote:
> On Wed, Mar 10, 2010 at 3:45 PM, Peter Matulis
> <peter.matulis at canonical.com> wrote:
>> Can anyone tell me whether the Karmic kernel has implemented a different
>> way of what it considers a process (as opposed to threads)?
>>
>> I have a situation where CPU load is zero on Karmic but considerably
>> higher in Jaunty and earlier.
>>
>> The scenario is a single java process with many threads.  The system has
>> 4 cores and only one java process should logically produce a negligible
>> CPU load but why was this not the case with earlier kernels?  Has
>> something changed in Karmic that would explain what I'm seeing?
> 
> I doubt that to be the case. Have you been able to get more data for
> your bug [1]?
> 
> Thanks,
> Chase
> 
> [1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/513848

Yes, but I couldn't get as much CPU usage out of the Karmic test.  My
'top' results show the following:

Cpu1  :  0.3%us,  0.6%sy
Cpu2  :  2.4%us,  0.6%sy
Cpu3  :  9.1%us,  1.8%sy
Cpu4  : 16.0%us,  7.4%sy

With a load of 0.00 across the board.

Now since CPU1 has such a low usage it makes sense that load is
negligible since that CPU is always available.  It seems that the
question is now:

Why the CPU usage is so much different between Karmic and Jaunty in this
 (single process/multiple thread) scenario.

-- 
Peter Matulis         |   GPG 34F740E8
Ubuntu Support Team   |   Canonical Ltd. (canonical.com)