On Thu, Sep 10, 2015 at 01:10:19PM +0100, Morten Rasmussen wrote: > > > so it appear to be intended to be using low resolution like load_avg > > > (weight is scaled down before it is passed into __update_load_avg()), > > > but util_avg is shifted up to high resolution. It should be: > > > > > > sa->util_avg = (sa->util_sum << (SCHED_LOAD_SHIFT - > > > SCHED_LOAD_SHIFT)) / LOAD_AVG_MAX; > > > > you probably mean (SCHED_LOAD_SHIFT - SCHED_LOAD_RESOLUTION) > > Yes. Thanks for providing the right expression. There seems to be enough > confusion in this thread already :) And yes, it is my bad in the first place, sorry, I did not think it though :)
> > The goal of this patchset is to be able to scale util_avg in the range > > of cpu capacity so why don't we directly initialize it with > > sa->util_avg = SCHED_CAPACITY_SCALE; Yes, we should, and specifically, it is bacause we can combine the resolution thing for util% * capacity%, so we only need to use the resolution once. > > and then use > > > > sa->util_avg = (sa->util_sum << SCHED_CAPACITY_SHIFT) / LOAD_AVG_MAX; > > > > so we don't have to take care of high and low load resolution > > That works for me, except that the left-shift has gone be PeterZ's > optimization patch posted earlier in this thread. It is changing > util_sum to scaled by capacity instead of being the pure geometric > series which requires the left shift at the end when we divide by > LOAD_AVG_MAX. So it should be equivalent to what you are proposing if we > change the initialization to your proposal too. I previously initialized the util_sum as: sa->util_sum = LOAD_AVG_MAX; it is because wihout capacity adjustment, this can save some multiplications in __update_load_avg(), but actually if we do capacity adjustment, we must multiply anyway, so it is better we initialize it as: sa->util_sum = sa->util_avg * LOAD_AVG_MAX; Anyway, with the patch I posted in the other email in this thread, we can fix all this very clearly, I hope so. I did not post a fix patch, it is because the solutions are already there, it is just how we make it look better, and you can provide it in your new version. Thanks, Yuyang -- 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/
