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7158457: division by zero in adaptiveweightedaverage

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Add ceiling to AdaptiveWeightedAverage

Reviewed-by: ysr, iveresov
This commit is contained in:
Mikael Vidstedt 2012-05-15 00:56:06 +02:00
parent 17b26a6a0c
commit c23595da74
2 changed files with 24 additions and 8 deletions
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14
hotspot/src/share/vm/gc_implementation/shared/gcUtil.cpp
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@ -31,9 +31,15 @@ float AdaptiveWeightedAverage::compute_adaptive_average(float new_sample,
float average) {
// We smooth the samples by not using weight() directly until we've
// had enough data to make it meaningful. We'd like the first weight
// used to be 1, the second to be 1/2, etc until we have 100/weight
// samples.
unsigned count_weight = 100/count();
// used to be 1, the second to be 1/2, etc until we have
// OLD_THRESHOLD/weight samples.
unsigned count_weight = 0;
// Avoid division by zero if the counter wraps (7158457)
if (!is_old()) {
count_weight = OLD_THRESHOLD/count();
}
unsigned adaptive_weight = (MAX2(weight(), count_weight));
float new_avg = exp_avg(average, new_sample, adaptive_weight);
@ -43,8 +49,6 @@ float AdaptiveWeightedAverage::compute_adaptive_average(float new_sample,
void AdaptiveWeightedAverage::sample(float new_sample) {
increment_count();
assert(count() != 0,
"Wraparound -- history would be incorrectly discarded");
// Compute the new weighted average
float new_avg = compute_adaptive_average(new_sample, average());