>>> On Thu, Feb 14, 2008 at 1:15 PM, in message <[EMAIL PROTECTED]>, Paul Jackson <[EMAIL PROTECTED]> wrote: > Peter wrote of: >> the lack of rd->load_balance. > > Could you explain to me a bit what that means? > > Does this mean that the existing code would, by default (default being > a single sched domain, covering the entire system's CPUs) load balance > across the entire system, but with your rework, not so load balance > there? That seems unlikely. > > In any event, from my rather cpuset-centric perspective, there are only > two common cases to consider. > > 1. In the default case, build_sched_domains() gets called once, > at init, with a cpu_map of all non-isolated CPUs, and we should > forever after load balance across all those non-isolated CPUs. > > 2. In some carefully managed systems using the per-cpuset > 'sched_load_balance' flags, we tear down that first default > sched domain, by calling detach_destroy_domains() on it, and we > then setup some number of sched_domains (typically in the range > of two to ten, though I suppose we should design to scale to > hundreds of sched domains, on systems with thousands of CPUs) > by additional calls to build_sched_domains(), such that their > CPUs don't overlap (pairwise disjoint) and such that the union > of all their CPUs may, or may not, include all non-isolated CPUs > (some CPUs might be left 'out in the cold', intentionally, as > essentially additional isolated CPUs.) We would then expect load > balancing within each of these pair-wise disjoint sched domains, > but not between one of them and another.
Hi Paul, I think it will still work as you describe. We create a new root-domain object for each pair-wise disjoint sched-domain. In your case (1) above, we would only have one instance of a root-domain which contains (of course) a single instance of the rd->load_balance object. This would, in fact operate like the global variable that Peter is suggesting it replace (IIUC). However, for case (2), we would instantiate a root-domain object per pairwise-disjoint sched-domain, and therefore each one would have its own instance of rd->load_balance. HTH -Greg -- 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/
