On Tue, Sep 08, 2015 at 09:22:05AM +0200, Vincent Guittot wrote: > No, but > sa->util_avg = (sa->util_sum << SCHED_CAPACITY_SHIFT) / LOAD_AVG_MAX; > will fix the unit issue.
Tricky that, LOAD_AVG_MAX very much relies on the unit being 1<<10. And where load_sum already gets a factor 1024 from the weight multiplication, util_sum does not get such a factor, and all the scaling we do on it loose bits. So at the moment we go compute the util_avg value, we need to inflate util_sum with an extra factor 1024 in order to make it work. And seeing that we do the shift up on sa->util_sum without consideration of overflow, would it not make sense to add that factor before the scaling and into the addition? Now, given all that, units are a complete mess here, and I'd not mind something like: #if (SCHED_LOAD_SHIFT - SCHED_LOAD_RESOLUTION) != SCHED_CAPACITY_SHIFT #error "something usefull" #endif somewhere near here. -- 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/
