On Tue, Mar 24, 2015 at 11:00:57AM +0100, Vincent Guittot wrote: > On 23 March 2015 at 14:19, Peter Zijlstra <pet...@infradead.org> wrote: > > On Fri, Feb 27, 2015 at 04:54:07PM +0100, Vincent Guittot wrote: > > > >> + unsigned long scale_freq = arch_scale_freq_capacity(NULL, cpu); > > > >> + sa->running_avg_sum += delta_w * scale_freq > >> + >> SCHED_CAPACITY_SHIFT; > > > > so the only thing that could be improved is somehow making this > > multiplication go away when the arch doesn't implement the function. > > > > But I'm not sure how to do that without #ifdef. > > > > Maybe a little something like so then... that should make the compiler > > get rid of those multiplications unless the arch needs them. > > yes, it removes useless multiplication when not used by an arch. > It also adds a constraint on the arch side which have to define > arch_scale_freq_capacity like below: > > #define arch_scale_freq_capacity xxx_arch_scale_freq_capacity > with xxx_arch_scale_freq_capacity an architecture specific function
Yeah, but it not being weak should make that a compile time warn/fail, which should be pretty easy to deal with. > If it sounds acceptable i can update the patch with your proposal ? I'll stick it to the end, I just wanted to float to patch to see if people had better solutions. -- 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/
