Messages in this thread | | | From | Vincent Guittot <> | Date | Wed, 25 Mar 2015 19:08:42 +0100 | Subject | Re: [PATCH v10 04/11] sched: Make sched entity usage tracking scale-invariant |
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On 25 March 2015 at 18:33, Peter Zijlstra <peterz@infradead.org> wrote: > On Tue, Mar 24, 2015 at 11:00:57AM +0100, Vincent Guittot wrote: >> On 23 March 2015 at 14:19, Peter Zijlstra <peterz@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.
ok. all other methods that i have tried, was removing the optimization when default arch_scale_freq_capacity was used
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