[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <1463338774-3324-2-git-send-email-yuyang.du@intel.com>
Date: Mon, 16 May 2016 02:59:26 +0800
From: Yuyang Du <yuyang.du@...el.com>
To: peterz@...radead.org, mingo@...nel.org,
linux-kernel@...r.kernel.org
Cc: bsegall@...gle.com, pjt@...gle.com, morten.rasmussen@....com,
vincent.guittot@...aro.org, dietmar.eggemann@....com,
juri.lelli@....com, Yuyang Du <yuyang.du@...el.com>
Subject: [RFC PATCH 1/9] sched/fair: Chance LOAD_AVG_MAX_N from 345 to 347
In commit 5b51f2f80b3b906ce59bd4dce6eca3c7f34cb1b9
Author: Paul Turner <pjt@...gle.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.du@...el.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 218f8e8..2635561 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 */
/* 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
Powered by blists - more mailing lists