On Mon, 2014-06-23 at 09:44 -0700, Jason Low wrote: > On Mon, 2014-06-23 at 18:22 +0200, Andi Kleen wrote: > > > So I don't get why we can't do the below; I think Jason tried to ask the > > > same... > > > > The important part for performance is to minimize the cache line transfers. > > Your > > unconditional variant would cause more dirty cache lines than Tim's, > > right? > > How about that change to the update_sg_lb_stats() call site along with: > > sgs->group_load += load; > sgs->sum_nr_running += rq->nr_running; > - if (overload && rq->nr_running > 1) > + if (!env->sd->parent && rq->nr_running > 1) > *overload = true; > > which keeps it as a conditional to avoid unnecessarily setting overload > when it's not used, and still get those benefits Peter mentioned.
I think this change will satisfy both needs. I'll re-spin a v3 patch with this modification if there're no objections. Tim -- 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/
