On 04/03/2013 01:38 PM, Michael Wang wrote: > On 04/03/2013 12:28 PM, Alex Shi wrote: > [snip] >> >> but the patch may cause some unfairness if this/prev cpu are not burst at >> same time. So could like try the following patch? > > I will try it later, some doubt below :) > > [snip] >> + >> + if (cpu_rq(this_cpu)->avg_idle < sysctl_sched_migration_cost || >> + cpu_rq(prev_cpu)->avg_idle < sysctl_sched_migration_cost) >> + burst= 1; >> + >> + /* use instant load for bursty waking up */ >> + if (!burst) { >> + load = source_load(prev_cpu, idx); >> + this_load = target_load(this_cpu, idx); >> + } else { >> + load = cpu_rq(prev_cpu)->load.weight; >> + this_load = cpu_rq(this_cpu)->load.weight; > > Ok, my understanding is, we want pull if 'prev_cpu' is burst, and don't > want pull if 'this_cpu' is burst, correct?
Nope, as my thought, a burst cpu doesn't mean it has heavy load than others, so we still need to compare their load on the same condition. > > And we do this by guess the load higher or lower, is that right? ditto. > > And I think target_load() is capable enough to choose the higher load, > if 'cpu_rq(cpu)->load.weight' is really higher, the results will be the > same. > > So what about this: > > /* prefer higher load if burst */ > load = burst_prev ? > target_load(prev_cpu, idx) : source_load(prev_cpu, idx); > > this_load = target_load(this_cpu, idx); here, the idx is zero, so source_load and target load is same. > > Regards, > Michael Wang > >> + } >> >> /* >> * If sync wakeup then subtract the (maximum possible) >> > -- Thanks Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/