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

Joe Perches
2016-04-08T10:31:47Z

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.