Re: ppc32: Weird process scheduling behaviour with 2.6.24-rc

On Fri, 2008-01-25 at 18:25 +1100, Benjamin Herrenschmidt wrote:

On Fri, 2008-01-25 at 18:03 +1100, Benjamin Herrenschmidt wrote:

quoted

On Fri, 2008-01-25 at 17:54 +1100, Benjamin Herrenschmidt wrote:

quoted

Here, I do the test of running 4 times the repro-case provided by Michel
with nice 19 and a dd eating CPU with nice 0.

Without this option, I get the dd at 100% and the nice 19 shells down
below it with whatever is left of the CPUs.

With this option, dd gets about 50% of one CPU and the niced processes
still get most of the time.

FYI. This is a 4 way G5 (ppc64)

I also tested responsiveness of X running with or without that option
and with niced CPU eaters in the background (still 4 of them, one per
CPU), and I can confirm Michel observations, it gets very sluggish
(maybe not -as- bad as his but still pretty annoying) with the fair
group scheduler enabled.

Here, X is running with nice=0

Curious, sounds like an issue with the group load balancer, vatsa, any
ideas?