On Jan 29, 2008 6:47 AM, Srivatsa Vaddagiri <[EMAIL PROTECTED]> wrote:
> IMHO this is expected results and if someone really needs to cut down > this latency, they can reduce sysctl_sched_latency (which will be bad > from perf standpoint, as we will cause more cache thrashing with that). Thank you very much for the detailed explanation Srivatsa, that made a lot of sense. Unfortunately, it means I'll disable FAIR_USER_SCHED as I initially thought these latencies were caused by my local patches that give each group a load proportional to the max load of its elements. Anyway, I don't absolutely need a fair user scheduler on my laptop, but low latencies in the default configuration are nice to have. I just thought about something to restore low latencies with FAIR_GROUP_SCHED, but it's possibly utter nonsense, so bear with me ;-) The idea would be to reverse the trees upside down. The scheduler would only see tasks (on the leaves) so could apply its interactivity magic, but the hierarchical groups would be used to compute dynamic loads for each task according to their position in the tree: - now: - we schedule each level of the tree starting from the root - with my proposition: - we schedule tasks like with !FAIR_GROUP_SCHED, but calc_delta_fair() would traverse the tree starting from the leaves to compute the dynamic load. Thanks. -- Guillaume -- 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/