On 26/02/2021 09:41, Peter Zijlstra wrote:
> On Thu, Feb 25, 2021 at 04:58:20PM +0000, Vincent Donnefort wrote:
>> +#define UTIL_EST_MARGIN (SCHED_CAPACITY_SCALE / 100)
>> +
>> /*
>> - * Check if a (signed) value is within a specified (unsigned) margin,
>> + * Check if a (signed) value is within the (unsigned) util_est margin,
>> * based on the observation that:
>> *
>> * abs(x) < y := (unsigned)(x + y - 1) < (2 * y - 1)
>> *
>> - * NOTE: this only works when value + maring < INT_MAX.
>> + * NOTE: this only works when value + UTIL_EST_MARGIN < INT_MAX.
>> */
>> -static inline bool within_margin(int value, int margin)
>> +static inline bool util_est_within_margin(int value)
>> {
>> - return ((unsigned int)(value + margin - 1) < (2 * margin - 1));
>> + return ((unsigned int)(value + UTIL_EST_MARGIN - 1) <
>> + (2 * UTIL_EST_MARGIN - 1));
>> }
>
>> - if (within_margin(last_ewma_diff, (SCHED_CAPACITY_SCALE / 100)))
>> + if (util_est_within_margin(last_ewma_diff)) {
>
> What was the purpose of this change? What was a generic helper is now
> super specific.
I guess because it was only ever used in util_est for last_ewma_diff.
It's now used for last_ewma_diff and last_enqueued_diff, still only for
util_est though and both times with the same margin
(SCHED_CAPACITY_SCALE / 100)).
Vincent D. should be back on Wed from hols.