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src/hotspot/share/gc/g1/g1HeapSizingPolicy.cpp
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rev 59304 : [mq]: 8245088-provide-log-information-about-heap-expansion
*** 48,59 ****
_ratio_over_threshold_count = 0;
_ratio_over_threshold_sum = 0.0;
_pauses_since_start = 0;
}
! double G1HeapSizingPolicy::scale_with_heap(double pause_time_ratio) {
! double threshold = pause_time_ratio;
// If the heap is at less than half its maximum size, scale the threshold down,
// to a limit of 1%. Thus the smaller the heap is, the more likely it is to expand,
// though the scaling code will likely keep the increase small.
if (_g1h->capacity() <= _g1h->max_capacity() / 2) {
threshold *= (double)_g1h->capacity() / (double)(_g1h->max_capacity() / 2);
--- 48,59 ----
_ratio_over_threshold_count = 0;
_ratio_over_threshold_sum = 0.0;
_pauses_since_start = 0;
}
! double G1HeapSizingPolicy::scale_with_heap(double upper_threshold) {
! double threshold = upper_threshold;
// If the heap is at less than half its maximum size, scale the threshold down,
// to a limit of 1%. Thus the smaller the heap is, the more likely it is to expand,
// though the scaling code will likely keep the increase small.
if (_g1h->capacity() <= _g1h->max_capacity() / 2) {
threshold *= (double)_g1h->capacity() / (double)(_g1h->max_capacity() / 2);
*** 61,97 ****
}
return threshold;
}
size_t G1HeapSizingPolicy::expansion_amount() {
assert(GCTimeRatio > 0, "must be");
double long_term_pause_time_ratio = _analytics->long_term_pause_time_ratio();
double short_term_pause_time_ratio = _analytics->short_term_pause_time_ratio();
size_t expand_bytes = 0;
if (_g1h->capacity() == _g1h->max_capacity()) {
! log_trace(gc, ergo, heap)("Can not expand (heap already fully expanded) "
! "long term GC overhead: %1.2f%% committed: " SIZE_FORMAT "B",
! long_term_pause_time_ratio * 100.0, _g1h->capacity());
!
clear_ratio_check_data();
return expand_bytes;
}
- const double pause_time_ratio = 1.0 / (1.0 + GCTimeRatio);
-
- double threshold = scale_with_heap(pause_time_ratio);
-
// If the last GC time ratio is over the threshold, increment the count of
// times it has been exceeded, and add this ratio to the sum of exceeded
// ratios.
if (short_term_pause_time_ratio > threshold) {
_ratio_over_threshold_count++;
_ratio_over_threshold_sum += short_term_pause_time_ratio;
}
// Check if we've had enough GC time ratio checks that were over the
// threshold to trigger an expansion. We'll also expand if we've
// reached the end of the history buffer and the average of all entries
// is still over the threshold. This indicates a smaller number of GCs were
// long enough to make the average exceed the threshold.
--- 61,123 ----
}
return threshold;
}
+ static void log(const char* prefix,
+ double short_term_pause_time_ratio,
+ double long_term_pause_time_ratio,
+ double threshold,
+ double pause_time_ratio,
+ bool fully_expanded,
+ size_t resize_bytes) {
+
+ log_debug(gc, ergo, heap)("%s "
+ "short term pause time ratio %1.2f%% long term pause time ratio %1.2f%% "
+ "threshold %1.2f%% pause time ratio %1.2f%% fully expanded %d "
+ "resize by " SIZE_FORMAT "B",
+ prefix,
+ short_term_pause_time_ratio * 100.0,
+ long_term_pause_time_ratio * 100.0,
+ threshold * 100.0,
+ pause_time_ratio * 100.0,
+ fully_expanded,
+ resize_bytes);
+ }
+
size_t G1HeapSizingPolicy::expansion_amount() {
assert(GCTimeRatio > 0, "must be");
double long_term_pause_time_ratio = _analytics->long_term_pause_time_ratio();
double short_term_pause_time_ratio = _analytics->short_term_pause_time_ratio();
+ const double pause_time_ratio = 1.0 / (1.0 + GCTimeRatio);
+ double threshold = scale_with_heap(pause_time_ratio);
+
size_t expand_bytes = 0;
if (_g1h->capacity() == _g1h->max_capacity()) {
! log("Heap expansion: Can not expand (heap already fully expanded)",
! short_term_pause_time_ratio, long_term_pause_time_ratio, threshold, pause_time_ratio, true, 0);
clear_ratio_check_data();
return expand_bytes;
}
// If the last GC time ratio is over the threshold, increment the count of
// times it has been exceeded, and add this ratio to the sum of exceeded
// ratios.
if (short_term_pause_time_ratio > threshold) {
_ratio_over_threshold_count++;
_ratio_over_threshold_sum += short_term_pause_time_ratio;
}
+
+ log_trace(gc, ergo, heap)("Heap expansion triggers: pauses since start: %u "
+ "num prev pauses for heuristics: %u "
+ "ratio over threshold count: %u",
+ _pauses_since_start,
+ _num_prev_pauses_for_heuristics,
+ _ratio_over_threshold_count);
+
// Check if we've had enough GC time ratio checks that were over the
// threshold to trigger an expansion. We'll also expand if we've
// reached the end of the history buffer and the average of all entries
// is still over the threshold. This indicates a smaller number of GCs were
// long enough to make the average exceed the threshold.
*** 144,165 ****
scale_factor = 1 + ((ratio_delta - StartScaleUpAt) / ScaleUpRange);
scale_factor = MIN2(scale_factor, MaxScaleUpFactor);
}
}
- log_debug(gc, ergo, heap)("Attempt heap expansion (recent GC overhead higher than threshold after GC) "
- "long term GC overhead: %1.2f%% threshold: %1.2f%% uncommitted: " SIZE_FORMAT "B "
- "base expansion amount and scale: " SIZE_FORMAT "B (%1.2f%%)",
- long_term_pause_time_ratio * 100.0, threshold * 100.0,
- uncommitted_bytes, expand_bytes, scale_factor * 100.0);
-
expand_bytes = static_cast<size_t>(expand_bytes * scale_factor);
// Ensure the expansion size is at least the minimum growth amount
// and at most the remaining uncommitted byte size.
! expand_bytes = MAX2(expand_bytes, min_expand_bytes);
! expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
clear_ratio_check_data();
} else {
// An expansion was not triggered. If we've started counting, increment
// the number of checks we've made in the current window. If we've
--- 170,184 ----
scale_factor = 1 + ((ratio_delta - StartScaleUpAt) / ScaleUpRange);
scale_factor = MIN2(scale_factor, MaxScaleUpFactor);
}
}
expand_bytes = static_cast<size_t>(expand_bytes * scale_factor);
// Ensure the expansion size is at least the minimum growth amount
// and at most the remaining uncommitted byte size.
! expand_bytes = clamp(min_expand_bytes, expand_bytes, uncommitted_bytes);
clear_ratio_check_data();
} else {
// An expansion was not triggered. If we've started counting, increment
// the number of checks we've made in the current window. If we've
*** 171,177 ****
--- 190,199 ----
clear_ratio_check_data();
}
}
}
+ log("Heap expansion:", short_term_pause_time_ratio, long_term_pause_time_ratio,
+ threshold, pause_time_ratio, false, expand_bytes);
+
return expand_bytes;
}
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