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8366434: THP not working properly with G1 after JDK-8345655

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Co-authored-by: Stefan Karlsson <stefank@openjdk.org>
Co-authored-by: Stefan Johansson <sjohanss@openjdk.org>
Reviewed-by: stefank, shade
This commit is contained in:
Stefan Johansson 2025-09-04 06:33:57 +00:00
parent 62bc7b7c42
commit a03302d41b
3 changed files with 156 additions and 2 deletions
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5
src/hotspot/share/memory/memoryReserver.cpp
View File

@ -110,12 +110,13 @@ static char* reserve_memory_inner(char* requested_address,
ReservedSpace MemoryReserver::reserve_memory(char* requested_address,
size_t size,
size_t alignment,
size_t page_size,
bool exec,
MemTag mem_tag) {
char* base = reserve_memory_inner(requested_address, size, alignment, exec, mem_tag);
if (base != nullptr) {
return ReservedSpace(base, size, alignment, os::vm_page_size(), exec, false /* special */);
return ReservedSpace(base, size, alignment, page_size, exec, false /* special */);
}
// Failed
@ -188,7 +189,7 @@ ReservedSpace MemoryReserver::reserve(char* requested_address,
}
// == Case 3 ==
return reserve_memory(requested_address, size, alignment, executable, mem_tag);
return reserve_memory(requested_address, size, alignment, page_size, executable, mem_tag);
}
ReservedSpace MemoryReserver::reserve(char* requested_address,

1
src/hotspot/share/memory/memoryReserver.hpp
View File

@ -34,6 +34,7 @@ class MemoryReserver : AllStatic {
static ReservedSpace reserve_memory(char* requested_address,
size_t size,
size_t alignment,
size_t page_size,
bool exec,
MemTag mem_tag);

152
test/hotspot/jtreg/gc/TestTransparentHugePagesHeap.java Normal file
View File

@ -0,0 +1,152 @@
/*
* Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
* 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
* 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.
*/
/*
* @test id=G1
* @summary Run tests with G1
* @library /test/lib
* @build jdk.test.lib.Platform
* @requires os.family == "linux"
* @requires vm.gc.G1
* @run driver TestTransparentHugePagesHeap G1
*/
/*
* @test id=Parallel
* @summary Run tests with Parallel
* @library /test/lib
* @build jdk.test.lib.Platform
* @requires os.family == "linux"
* @requires vm.gc.Parallel
* @run driver TestTransparentHugePagesHeap Parallel
*/
/*
* @test id=Serial
* @summary Run tests with Serial
* @library /test/lib
* @build jdk.test.lib.Platform
* @requires os.family == "linux"
* @requires vm.gc.Serial
* @run driver TestTransparentHugePagesHeap Serial
*/
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.Scanner;
import jdk.test.lib.os.linux.HugePageConfiguration;
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;
import jdk.test.lib.Platform;
import jtreg.SkippedException;
// We verify that the heap can be backed by THP by looking at the
// THPeligible field for the heap section in /proc/self/smaps. This
// field indicates if a mapping can use THP.
// THP mode 'always': this field is 1 whenever huge pages can be used
// THP mode 'madvise': this field is 1 if the mapping has been madvised
// as MADV_HUGEPAGE. In the JVM that should happen when the flag
// -XX:+UseTransparentHugePages is specified.
//
// Note: we don't verify if the heap is backed by huge pages because we
// can't know if the underlying system have any available.
public class TestTransparentHugePagesHeap {
public static void main(String args[]) throws Exception {
// To be able to detect large page use (esp. THP) somewhat reliably, we
// need at least kernel 3.8 to get the "VmFlags" tag in smaps.
// (Note: its still good we started the VM at least since this serves as a nice
// test for all manners of large page options).
if (Platform.getOsVersionMajor() < 3 ||
(Platform.getOsVersionMajor() == 3 && Platform.getOsVersionMinor() < 8)) {
throw new SkippedException("Kernel older than 3.8 - skipping this test.");
}
final HugePageConfiguration hugePageConfiguration = HugePageConfiguration.readFromOS();
if (!hugePageConfiguration.supportsTHP()) {
throw new SkippedException("THP is turned off");
}
OutputAnalyzer oa = ProcessTools.executeTestJava("-XX:+Use" + args[0] + "GC", "-Xmx128m", "-Xms128m", "-Xlog:pagesize:thp-%p.log", "-XX:+UseTransparentHugePages", VerifyTHPEnabledForHeap.class.getName());
oa.shouldHaveExitValue(0);
}
class VerifyTHPEnabledForHeap {
public static void main(String args[]) throws Exception {
String heapAddress = readHeapAddressInLog();
Path smaps = makeSmapsCopy();
final Pattern heapSection = Pattern.compile("^" + heapAddress + ".*");
final Pattern thpEligible = Pattern.compile("THPeligible:\\s+(\\d)\\s*");
Scanner smapsFile = new Scanner(smaps);
while (smapsFile.hasNextLine()) {
Matcher heapMatcher = heapSection.matcher(smapsFile.nextLine());
if (heapMatcher.matches()) {
// Found the first heap section, verify that it is THP eligible
while (smapsFile.hasNextLine()) {
Matcher m = thpEligible.matcher(smapsFile.nextLine());
if (m.matches()) {
if (Integer.parseInt(m.group(1)) == 1) {
// THPeligible is 1, heap can be backed by huge pages
return;
}
throw new RuntimeException("First heap section at 0x" + heapAddress + " is not THPeligible");
}
}
}
}
// Failed to verify THP for heap
throw new RuntimeException("Could not find heap section in smaps file");
}
private static String readHeapAddressInLog() throws Exception {
final Pattern heapAddress = Pattern.compile(".* Heap: .*base=(0x[0-9A-Fa-f]*).*");
Scanner logFile = new Scanner(Paths.get("thp-" + ProcessHandle.current().pid() + ".log"));
while (logFile.hasNextLine()) {
Matcher m = heapAddress.matcher(logFile.nextLine());
if (m.matches()) {
return Long.toHexString(Long.decode(m.group(1)));
}
}
throw new RuntimeException("Failed to parse heap address, failing test");
}
private static Path makeSmapsCopy() throws Exception {
Path src = Paths.get("/proc/self/smaps");
Path dest = Paths.get("smaps-copy-" + ProcessHandle.current().pid() + ".txt");
Files.copy(src, dest, StandardCopyOption.REPLACE_EXISTING);
return dest;
}
}
}