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Re: [PATCH] sched/fair: Optimize sum computation with a lookup table

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On Fri, 2016-04-08 at 10:07 +0800, Yuyang Du wrote:
> __compute_runnable_contrib() uses a loop to compute sum, whereas a
> table lookup can do it faster in a constant time.

Perhaps this becomes rather fragile code overly dependent on the
current #define values of LOAD_AVG_MAX_N and LOAD_AVG_PERIOD.

Perhaps this comment just above the definitions of LOAD_AVG_MAX_N
and LOAD_AVG_PERIOD should be updated to include this new table:

 * Note: The tables runnable_avg_yN_inv and runnable_avg_yN_sum are
 * dependent on this value.

Perhaps the __ prefix for __accumulated_sum_N32 is odd as both of
the runnable_avg_yN_ tables are not __ prefixed.

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[PATCH] sched/fair: Optimize sum computation with a lookup table Yuyang Du <yuyang.du@intel.com> - 2016-04-08 12:00 +0200
  Re: [PATCH] sched/fair: Optimize sum computation with a lookup table Joe Perches <joe@perches.com> - 2016-04-08 12:40 +0200
    Re: [PATCH] sched/fair: Optimize sum computation with a lookup table Peter Zijlstra <peterz@infradead.org> - 2016-04-08 13:00 +0200
      Re: [PATCH] sched/fair: Optimize sum computation with a lookup table Juri Lelli <juri.lelli@arm.com> - 2016-04-08 18:30 +0200
  Re: [PATCH] sched/fair: Optimize sum computation with a lookup table Peter Zijlstra <peterz@infradead.org> - 2016-04-08 12:50 +0200
  Re: [PATCH] sched/fair: Optimize sum computation with a lookup table Peter Zijlstra <peterz@infradead.org> - 2016-04-08 12:50 +0200
  Re: [PATCH] sched/fair: Optimize sum computation with a lookup table Morten Rasmussen <morten.rasmussen@arm.com> - 2016-04-08 13:30 +0200

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