2009-01-07, 02:32
alanwww1 Wrote:I think the kernel tries to use as few cores as possible leaving the rest of the cores idle to make them downclockable. It is perfectly reasonable if we generally using the kernel for normal tasks. This way we have a 4 core or and 8 core processor used just as much core as it is nneded to fulfill a certain task. But with video decoding i think it's not good. We want to use the cores evenly loaded, better have the two main threads stayed exclusively on one a specific core.
Maybe there is a kernel option for this, how the user want to optimalize his cpu core usage. I think this could be the difference of Hardy and Intrepid kernel that Hardy did not have this so called "energy optimalized" cpu usage. (I already tried to disable powernowd and also speedstep in BIOS with no change)
No. Please get ahold of some operating systems and computer architecture textbooks and give them a read before making any more outlandish assumptions. At least read up on the new linux process scheduler (it's called The Completely Fair Scheduler or CFS). It was enabled by ubuntu in 2.6.26 IIRC. It's not the job of the sch...
...my rant may have sparked an idea as to the cause. If the scheduler takes into account cache coherence, and there is significant spacial locality, it may stick both threads on the same core in an attempt avoid having the same data in multiple caches. Off to read myself...