Re: Problem: Load average of 6, no I/O, 25% idle time. Why?

["Timothy Normand Miller" <theosib@gmail.com>]

On Fri, Jul 18, 2008 at 9:28 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, 2008-07-18 at 08:49 -0400, Timothy Normand Miller wrote:
>> I have a four processor box, running three compute loads.  The kernel
>> I'm running is 2.6.25-gentoo-r5.
>>
>> One process has four threads, and it's niced to 19.
>> Another process has one thread and is niced to -10
>> The last process has one thread and is niced to 0
>>
>> One processor is always idle.
>>
>> If I change either the 0 to a -10 or the -10 to a zero, then all four
>> cores are properly utilized.

Interesting corollary:  If the only thing running is the one nice=19,
four-thread process, then there's about 4% idle time.  I have to raise
the priority to get the idle time to go away.  Since when do active
processes yield to idle time?

Two of my three loads are finished, so when this last one is done,
I'll try 2.6.26.  Was something like this actively discussed and fixed
between 2.6.25 and 2.6.26?

Thanks.


-- 
Timothy Normand Miller
http://www.cse.ohio-state.edu/~millerti
Open Graphics Project