On 10 August 2016 at 02:14, Yuyang Du <yuyang...@intel.com> wrote: > In commit 5b51f2f80b3b906ce59bd4dce6eca3c7f34cb1b9 > Author: Paul Turner <p...@google.com> > Date: Thu Oct 4 13:18:32 2012 +0200 > > sched: Make __update_entity_runnable_avg() fast > > Paul has a program to compute LOAD_AVG_MAX_N, which basically means > how many periods (at least) are needed for LOAD_AVG_MAX, and the result > of calc_conv(1024) is 345: > > long mult_inv(long c, int n) { > return (c * runnable_avg_yN_inv[n]) >> WMULT_SHIFT; > } > > void calc_conv(long n) { > long old_n; > int i = -1; > > printf("convergence (LOAD_AVG_MAX, LOAD_AVG_MAX_N)\n"); > do { > old_n = n; > n = mult_inv(n, 1) + 1024; > i++; > } while (n != old_n); > printf("%d> %ld\n", i - 1, n); > printf("\n"); > } > > The initial value of i is -1, which should be 1 as far as I can tell. > Accordingly, the final result of LOAD_AVG_MAX_N should be changed > from 345 to 347. > > Signed-off-by: Yuyang Du <yuyang...@intel.com> > --- > kernel/sched/fair.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 4088eed..997297b 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -666,7 +666,7 @@ static unsigned long task_h_load(struct task_struct *p); > */ > #define LOAD_AVG_PERIOD 32 > #define LOAD_AVG_MAX 47742 /* maximum possible load avg */ > -#define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_AVG_MAX > */ > +#define LOAD_AVG_MAX_N 347 /* number of full periods to produce LOAD_AVG_MAX > */
Acked-by: Vincent Guittot <vincent.gui...@linar.org> > > /* Give new sched_entity start runnable values to heavy its load in infant > time */ > void init_entity_runnable_average(struct sched_entity *se) > -- > 1.7.9.5 >