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Adjust the calls to align_timer() in the on-demand > > governor to pass the expected timer expiration as the first parameter. > > Internally, we have a report of a benchmark regressing ~6% with this change > on 4.20. > > s_time_t align_timer(s_time_t firsttick, uint64_t period) > { > if ( !period ) > return firsttick; > > return firsttick + (period - 1) - ((firsttick - 1) % period); > } > > The code rounds firsttick up to the next period: > > align_timer(0, period) -> 0 > align_timer(1, period) -> period > align_timer(period - 1, period) -> period > align_timer(period, period) -> period > align_timer(period + 1, period) -> 2 * period > > With the change of this patch adding the period before calling > align_timer(), the timer is set for two periods in the future. The only > exception is when firsttick % period == 0. I think that is unlikely to > happen since NOW() will always be a little after the period. Even if it did > happen, the timer would fire immediately, but the next timer would be set > for 1 period later. > > So I think we want to revert? Forgot to mention in the first reply, as I went straight into the technical side: thanks for finding and reporting this, we can hopefully get it sorted before the release. Roger.