I just noticed the changes to reschedule_idle() in the 2.4.5-ac
kernel. I suspect these are the changes made for:
o Fix off by one on real time pre-emption in scheduler
I'm curious if anyone has ran any benchmarks before and after
applying this fix.
The reason I ask is that during the development of my multi-queue
scheduler, I 'accidently' changed reschedule_idle code to trigger
a preemption if preemption_goodness() was greater than 0, as
opposed to greater than 1. I believe this is the same change made
to the ac kernel. After this change, we saw a noticeable drop in
performance for some benchmarks.
The drop in performance I saw could have been the result of a
combination of the change, and my multi-queue scheduler. However,
in any case aren't we now going to trigger more preemptions?
I understand that we need to make the fig to get the realtime
semantics correct, but we also need to be aware of performance in
the non-realtime case.
-- Mike Kravetz mkravetz@sequent.com IBM Linux Technology Center - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu Jun 07 2001 - 21:00:32 EST