Messages in this thread | | | Date | Thu, 26 Mar 2015 18:47:00 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v10 04/11] sched: Make sched entity usage tracking scale-invariant |
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On Thu, Mar 26, 2015 at 05:38:45PM +0000, Morten Rasmussen wrote: > Another potential solution is to stay with weak functions but move the > multiplication and shift into the arch_scale_*() functions by passing > the value we want to scale into the arch_scale_*() function. That way we > can completely avoid multiplication and shift in the default case (no > arch_scale*() implementations, which is better than what we have today. > > The only downside is that for frequency invariance we need three > arch_scale_freq_capacity() calls instead of two.
That would still result in unconditional function calls, which on some archs are _more_ expensive than 64bit mults.
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