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8371672: G1: G1YoungGenSizer handling of NewRatio, NewSize and MaxNewSize

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8370494: G1: NewSize not bounded by InitialHeapSize or MaxHeapSize

Reviewed-by: tschatzl, iwalulya
This commit is contained in:
Axel Boldt-Christmas 2025-11-17 07:33:33 +00:00
parent 7738131835
commit ce1adf63ea
1 changed files with 72 additions and 24 deletions
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96
src/hotspot/share/gc/g1/g1YoungGenSizer.cpp
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@ -25,47 +25,95 @@
#include "gc/g1/g1Arguments.hpp"
#include "gc/g1/g1HeapRegion.hpp"
#include "gc/g1/g1YoungGenSizer.hpp"
#include "gc/shared/gc_globals.hpp"
#include "logging/log.hpp"
#include "runtime/globals_extension.hpp"
G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults),
_use_adaptive_sizing(true), _min_desired_young_length(0), _max_desired_young_length(0) {
precond(!FLAG_IS_ERGO(NewRatio));
precond(!FLAG_IS_ERGO(NewSize));
precond(!FLAG_IS_ERGO(MaxNewSize));
// Figure out compatible young gen sizing policies.
// This will either use all default, NewRatio or a combination of NewSize and
// MaxNewSize. If both ratio and size is user specified NewRatio will be ignored.
const bool user_specified_NewRatio = !FLAG_IS_DEFAULT(NewRatio);
const bool user_specified_NewSize = !FLAG_IS_DEFAULT(NewSize);
const bool user_specified_MaxNewSize = !FLAG_IS_DEFAULT(MaxNewSize);
// MaxNewSize is updated every time the heap is resized (and when initialized),
// as such the value of MaxNewSize is only modified if it is also used by the
// young generation sizing. (If MaxNewSize is user specified).
if (!user_specified_NewRatio && !user_specified_NewSize && !user_specified_MaxNewSize) {
// Using Defaults.
return;
}
if (user_specified_NewRatio && !user_specified_NewSize && !user_specified_MaxNewSize) {
// Using NewRatio.
_sizer_kind = SizerNewRatio;
_use_adaptive_sizing = false;
return;
}
if (FLAG_IS_CMDLINE(NewRatio)) {
if (FLAG_IS_CMDLINE(NewSize) || FLAG_IS_CMDLINE(MaxNewSize)) {
log_warning(gc, ergo)("-XX:NewSize and -XX:MaxNewSize override -XX:NewRatio");
} else {
_sizer_kind = SizerNewRatio;
_use_adaptive_sizing = false;
return;
// NewRatio ignored at this point, issue warning if NewRatio was specified
// on the command line.
log_warning(gc, ergo)("-XX:NewSize and -XX:MaxNewSize overrides -XX:NewRatio");
}
assert(!FLAG_IS_DEFAULT(InitialHeapSize), "Initial heap size must be selected");
if (user_specified_NewSize && NewSize > InitialHeapSize) {
// If user specifed NewSize is larger than the InitialHeapSize truncate the value.
if (FLAG_IS_CMDLINE(NewSize)) {
log_warning(gc, ergo)("NewSize (%zuk) is greater than the initial heap size (%zuk). "
"A new NewSize of %zuk will be used.",
NewSize/K, InitialHeapSize/K, InitialHeapSize/K);
}
FLAG_SET_ERGO(NewSize, InitialHeapSize);
}
assert(!FLAG_IS_DEFAULT(MaxHeapSize), "Max heap size must be selected");
if (user_specified_MaxNewSize && MaxNewSize > MaxHeapSize) {
// If user specifed MaxNewSize is larger than the MaxHeapSize truncate the value.
if (FLAG_IS_CMDLINE(MaxNewSize)) {
log_warning(gc, ergo)("MaxNewSize (%zuk) greater than the entire heap (%zuk). "
"A new MaxNewSize of %zuk will be used.",
MaxNewSize/K, MaxHeapSize/K, MaxHeapSize/K);
}
FLAG_SET_ERGO(MaxNewSize, MaxHeapSize);
}
if (NewSize > MaxNewSize) {
// Either NewSize, MaxNewSize or both have been specified and are incompatible.
// In either case set MaxNewSize to the value of NewSize.
if (FLAG_IS_CMDLINE(MaxNewSize)) {
log_warning(gc, ergo)("NewSize (%zuk) is greater than the MaxNewSize (%zuk). "
"A new max generation size of %zuk will be used.",
log_warning(gc, ergo)("NewSize (%zuk) is greater than MaxNewSize (%zuk). "
"A new MaxNewSize of %zuk will be used.",
NewSize/K, MaxNewSize/K, NewSize/K);
}
FLAG_SET_ERGO(MaxNewSize, NewSize);
}
if (FLAG_IS_CMDLINE(NewSize)) {
_min_desired_young_length = MAX2((uint) (NewSize / G1HeapRegion::GrainBytes),
1U);
if (FLAG_IS_CMDLINE(MaxNewSize)) {
_max_desired_young_length =
MAX2((uint) (MaxNewSize / G1HeapRegion::GrainBytes),
1U);
_sizer_kind = SizerMaxAndNewSize;
_use_adaptive_sizing = _min_desired_young_length != _max_desired_young_length;
} else {
_sizer_kind = SizerNewSizeOnly;
}
} else if (FLAG_IS_CMDLINE(MaxNewSize)) {
_max_desired_young_length =
MAX2((uint) (MaxNewSize / G1HeapRegion::GrainBytes),
1U);
if (user_specified_NewSize) {
_min_desired_young_length = MAX2((uint)(NewSize / G1HeapRegion::GrainBytes), 1U);
}
if (user_specified_MaxNewSize) {
_max_desired_young_length = MAX2((uint)(MaxNewSize / G1HeapRegion::GrainBytes), 1U);
}
if (user_specified_NewSize && user_specified_MaxNewSize) {
_sizer_kind = SizerMaxAndNewSize;
_use_adaptive_sizing = _min_desired_young_length != _max_desired_young_length;
} else if (user_specified_NewSize) {
_sizer_kind = SizerNewSizeOnly;
} else {
postcond(user_specified_MaxNewSize);
_sizer_kind = SizerMaxNewSizeOnly;
}
}