7146246: G1: expose some of the -XX flags that drive which old regions to collect during mixed GCs
Summary: Make two G1 cmd line flags available in product builds: G1HeapWastePercent (previously called: G1OldReclaimableThresholdPercent) and G1MixedGCCountTarget (previous called: G1MaxMixedGCNum). Also changed the default of the former from 1% to 5% and the default for G1OldCSetRegionLiveThresholdPercent to 90%.
Reviewed-by: azeemj, jwilhelm, johnc
--- a/hotspot/src/share/vm/gc_implementation/g1/collectionSetChooser.cpp Mon Mar 12 14:59:00 2012 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/collectionSetChooser.cpp Fri Mar 23 10:53:19 2012 -0400
@@ -285,7 +285,7 @@
// that the result is the same during all mixed GCs that follow a cycle.
const size_t region_num = (size_t) _length;
- const size_t gc_num = (size_t) G1MaxMixedGCNum;
+ const size_t gc_num = (size_t) G1MixedGCCountTarget;
size_t result = region_num / gc_num;
// emulate ceiling
if (result * gc_num < region_num) {
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp Mon Mar 12 14:59:00 2012 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp Fri Mar 23 10:53:19 2012 -0400
@@ -2608,7 +2608,7 @@
size_t reclaimable_bytes = cset_chooser->remainingReclaimableBytes();
size_t capacity_bytes = _g1->capacity();
double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
- double threshold = (double) G1OldReclaimableThresholdPercent;
+ double threshold = (double) G1HeapWastePercent;
if (perc < threshold) {
ergo_verbose4(ErgoMixedGCs,
false_action_str,
--- a/hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp Mon Mar 12 14:59:00 2012 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp Fri Mar 23 10:53:19 2012 -0400
@@ -299,17 +299,16 @@
"Percentage (0-100) of the heap size to use as maximum " \
"young gen size.") \
\
- develop(uintx, G1OldCSetRegionLiveThresholdPercent, 95, \
+ develop(uintx, G1OldCSetRegionLiveThresholdPercent, 90, \
"Threshold for regions to be added to the collection set. " \
"Regions with more live bytes that this will not be collected.") \
\
- develop(uintx, G1OldReclaimableThresholdPercent, 1, \
- "Threshold for the remaining old reclaimable bytes, expressed " \
- "as a percentage of the heap size. If the old reclaimable bytes " \
- "are under this we will not collect them with more mixed GCs.") \
+ product(uintx, G1HeapWastePercent, 5, \
+ "Amount of space, expressed as a percentage of the heap size, " \
+ "that G1 is willing not to collect to avoid expensive GCs.") \
\
- develop(uintx, G1MaxMixedGCNum, 4, \
- "The maximum desired number of mixed GCs after a marking cycle.") \
+ product(uintx, G1MixedGCCountTarget, 4, \
+ "The target number of mixed GCs after a marking cycle.") \
\
develop(uintx, G1OldCSetRegionThresholdPercent, 10, \
"An upper bound for the number of old CSet regions expressed " \