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8245754: Shenandoah: ditch ShenandoahAlwaysPreTouch

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Reviewed-by: rkennke
This commit is contained in:
Aleksey Shipilev 2020-05-26 09:30:17 +02:00
parent 66f6c8c3fe
commit ad7f611149
3 changed files with 3 additions and 16 deletions

10
src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp

@ -143,20 +143,12 @@ void ShenandoahArguments::initialize() {
#endif // ASSERT
#endif // COMPILER2
if (AlwaysPreTouch) {
// Shenandoah handles pre-touch on its own. It does not let the
// generic storage code to do the pre-touch before Shenandoah has
// a chance to do it on its own.
FLAG_SET_DEFAULT(AlwaysPreTouch, false);
FLAG_SET_DEFAULT(ShenandoahAlwaysPreTouch, true);
}
// Record more information about previous cycles for improved debugging pleasure
if (FLAG_IS_DEFAULT(LogEventsBufferEntries)) {
FLAG_SET_DEFAULT(LogEventsBufferEntries, 250);
}
if (ShenandoahAlwaysPreTouch) {
if (AlwaysPreTouch) {
if (!FLAG_IS_DEFAULT(ShenandoahUncommit)) {
warning("AlwaysPreTouch is enabled, disabling ShenandoahUncommit");
}

6
src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp

@ -155,7 +155,7 @@ jint ShenandoahHeap::initialize() {
size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
if (ShenandoahAlwaysPreTouch) {
if (AlwaysPreTouch) {
// Enabled pre-touch means the entire heap is committed right away.
init_byte_size = max_byte_size;
}
@ -344,9 +344,7 @@ jint ShenandoahHeap::initialize() {
_free_set->rebuild();
}
if (ShenandoahAlwaysPreTouch) {
assert(!AlwaysPreTouch, "Should have been overridden");
if (AlwaysPreTouch) {
// For NUMA, it is important to pre-touch the storage under bitmaps with worker threads,
// before initialize() below zeroes it with initializing thread. For any given region,
// we touch the region and the corresponding bitmaps from the same thread.

3
src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp

@ -300,9 +300,6 @@
diagnostic(bool, ShenandoahAllocFailureALot, false, \
"Testing: make lots of artificial allocation failures.") \
\
diagnostic(bool, ShenandoahAlwaysPreTouch, false, \
"Pre-touch heap memory, overrides global AlwaysPreTouch.") \
\
experimental(intx, ShenandoahMarkScanPrefetch, 32, \
"How many objects to prefetch ahead when traversing mark bitmaps."\
"Set to 0 to disable prefetching.") \