Messages in this thread Patch in this message | | | From | Leo Yan <> | Subject | [PATCH] sched/fair: refine maximum periods for decay_load | Date | Fri, 5 Aug 2016 14:34:00 +0800 |
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In current code, decay_load() will consider to set load value to zero after passing 32*64 ms. So this means max_load * (0.5^64) ~= 0.
Kernel can support maximum number of processes and threads to 2^29 and set task with highest priority with nice=-20 (weight = 88761). So in worst case, one CPU may have maximum load value is:
max_load = 2^29 * 88761 < 2^46
In theory after pass 46 periods we can ensure load value will be decayed to zero. So this patch is to change maximum periods from 64 to 48.
Signed-off-by: Leo Yan <leo.yan@linaro.org> --- 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 e342159..55cb134 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2622,7 +2622,7 @@ static __always_inline u64 decay_load(u64 val, u64 n) if (!n) return val; - else if (unlikely(n > LOAD_AVG_PERIOD * 63)) + else if (unlikely(n > LOAD_AVG_PERIOD * 47)) return 0; /* after bounds checking we can collapse to 32-bit */ -- 1.9.1
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