* Tong Li <[EMAIL PROTECTED]> wrote: > > you need to measure it over longer periods of time. Its not worth > > balancing for such a thing in any high-frequency manner. (we'd trash > > the cache constantly migrating tasks back and forth.) > > I have some data below, but before that, I'd like to say, at the same > load balancing rate, my proposed approach would allow us to have > fairness on the order of seconds. I'm less concerned about trashing > the cache. The important thing is to have a knob that allow users to > trade off fairness and performance based on their needs. [...]
such a knob already exists to a certain degree, but i havent tested its full effects on SMP fairness yet. If you pull my scheduler tree: git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched.git and if you enable CONFIG_SCHED_DEBUG, then all the sched-domain parameters become runtime tunable under /proc/sys/cpu*. Could you try to increase the cross-CPU rebalancing frequency and see how it impacts the precision of your measurement? Tune 'min_interval' and 'max_interval' down to increase the frequency of rebalancing. Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/