evie/android_kernel_oneplus_msm8998
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sched: fix overflow in scaled execution time calculation

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Task execution time in nanoseconds and CPU cycle counters are large
enough to cause overflow when we multiply both.  Avoid overflow by
calculating frequency separately.

Change-Id: I076d9ecd27cb1c1f11578f009ebe1a19c1619454
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
This commit is contained in:
Joonwoo Park 2016-06-10 16:16:19 -07:00 • committed by Kyle Yan
parent c07e88c80f
commit 14ac5ed8b8
1 changed files with 3 additions and 2 deletions
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5
kernel/sched/core.c
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@ -1941,9 +1941,10 @@ static inline u64 scale_exec_time(u64 delta, struct rq *rq)
{
int cpu = cpu_of(rq);
int sf;
u32 freq;
delta = DIV64_U64_ROUNDUP(delta * rq->cc.cycles,
max_possible_freq * rq->cc.time);
freq = cpu_cycles_to_freq(rq->cc.cycles, rq->cc.time);
delta = DIV64_U64_ROUNDUP(delta * freq, max_possible_freq);
sf = DIV_ROUND_UP(cpu_efficiency(cpu) * 1024, max_possible_efficiency);
delta *= sf;