I ran the VolanoMark and TPC-H benchmarks on an 8 CPU system
to observe the differences when changing the value at which
preemptions are triggered. I used the 2.4.5 kernel as a basis
and only changed the 'max_prio = ' statement in reschedule_idle()
to change the preemption trigger threshold. In the 2.4.5 kernel
the value of max_prio is set to 1.
The results:
In VolanoMark, changing the preemption trigger from 1 to 0
resulted in a 4% drop in throughput.
In TPC-H there was virtually no difference when going from
1 to 0. If anything, the results were slightly better with
0 as a threshold value as opposed to 1.
My guess is that the threshold value was changed from 0 to
1 in the 2.4 kernel for better performance with some workload.
Anyone remember what that workload was/is?
-- 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 - 21:00:42 EST