jdk-24/src/hotspot/share/runtime/safepointMechanism.cpp
Robbin Ehn 104ecb2dd1 8189941: Implementation JEP 312: Thread-local handshake
Introduce a way to execute a callback on threads without performing a global VM safepoint. Make it both possible and cheap to stop individual threads and not just all threads or none.

Co-authored-by: Mikael Gerdin <mikael.gerdin@oracle.com>
Co-authored-by: Erik Osterlund <erik.osterlund@oracle.com>
Reviewed-by: mdoerr, neliasso, acorn, aph, coleenp, dholmes
2017-08-31 10:00:28 +02:00

85 lines
3.5 KiB
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/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* 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
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*
* 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
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*
* 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.
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#include "precompiled.hpp"
#include "logging/log.hpp"
#include "runtime/globals.hpp"
#include "runtime/os.hpp"
#include "runtime/safepointMechanism.inline.hpp"
#include "utilities/globalDefinitions.hpp"
SafepointMechanism::PollingType SafepointMechanism::_polling_type = SafepointMechanism::_global_page_poll;
void* SafepointMechanism::_poll_armed_value;
void* SafepointMechanism::_poll_disarmed_value;
void SafepointMechanism::default_initialize() {
if (ThreadLocalHandshakes) {
set_uses_thread_local_poll();
const size_t page_size = os::vm_page_size();
const size_t allocation_size = 2 * page_size;
char* polling_page = os::reserve_memory(allocation_size, NULL, page_size);
os::commit_memory_or_exit(polling_page, allocation_size, false, "Unable to commit Safepoint polling page");
char* bad_page = polling_page;
char* good_page = polling_page + page_size;
os::protect_memory(bad_page, page_size, os::MEM_PROT_NONE);
os::protect_memory(good_page, page_size, os::MEM_PROT_READ);
log_info(os)("SafePoint Polling address, bad (protected) page:" INTPTR_FORMAT ", good (unprotected) page:" INTPTR_FORMAT, p2i(bad_page), p2i(good_page));
os::set_polling_page((address)(bad_page));
intptr_t poll_page_val = reinterpret_cast<intptr_t>(bad_page);
_poll_armed_value = reinterpret_cast<void*>(poll_page_val | poll_bit());
_poll_disarmed_value = good_page;
} else {
const size_t page_size = os::vm_page_size();
char* polling_page = os::reserve_memory(page_size, NULL, page_size);
os::commit_memory_or_exit(polling_page, page_size, false, "Unable to commit Safepoint polling page");
os::protect_memory(polling_page, page_size, os::MEM_PROT_READ);
log_info(os)("SafePoint Polling address: " INTPTR_FORMAT, p2i(polling_page));
os::set_polling_page((address)(polling_page));
}
}
void SafepointMechanism::initialize_header(JavaThread* thread) {
disarm_local_poll(thread);
}
void SafepointMechanism::initialize_serialize_page() {
if (!UseMembar) {
const size_t page_size = os::vm_page_size();
char* serialize_page = os::reserve_memory(page_size, NULL, page_size);
os::commit_memory_or_exit(serialize_page, page_size, false, "Unable to commit memory serialization page");
log_info(os)("Memory Serialize Page address: " INTPTR_FORMAT, p2i(serialize_page));
os::set_memory_serialize_page((address)(serialize_page));
}
}
void SafepointMechanism::initialize() {
pd_initialize();
initialize_serialize_page();
}