8231198: Shenandoah: heap walking should visit all roots most of the time
Reviewed-by: zgu, rkennke
/*
* Copyright (c) 2019, Red Hat, Inc. All rights reserved.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "gc/shenandoah/shenandoahPassiveMode.hpp"
#include "gc/shenandoah/heuristics/shenandoahPassiveHeuristics.hpp"
#include "logging/log.hpp"
#include "logging/logTag.hpp"
void ShenandoahPassiveMode::initialize_flags() const {
// Do not allow concurrent cycles.
FLAG_SET_DEFAULT(ExplicitGCInvokesConcurrent, false);
FLAG_SET_DEFAULT(ShenandoahImplicitGCInvokesConcurrent, false);
// Passive runs with max speed, reacts on allocation failure.
FLAG_SET_DEFAULT(ShenandoahPacing, false);
// No need for evacuation reserve with Full GC, only for Degenerated GC.
if (!ShenandoahDegeneratedGC) {
SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahEvacReserve, 0);
}
// Disable known barriers by default.
SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahLoadRefBarrier);
SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahSATBBarrier);
SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahKeepAliveBarrier);
SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahStoreValEnqueueBarrier);
SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCASBarrier);
SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCloneBarrier);
// Final configuration checks
// No barriers are required to run.
}
ShenandoahHeuristics* ShenandoahPassiveMode::initialize_heuristics() const {
if (ShenandoahGCHeuristics != NULL) {
return new ShenandoahPassiveHeuristics();
}
ShouldNotReachHere();
return NULL;
}