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/*
* Copyright (c) 2014, 2024, Alibaba Group Holding Limited. All rights reserved.
* Copyright (c) 2024, 2025, Red Hat Inc.
* 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.
*/
package gc;
/**
* @test id=ParallelCollector
* @summary tests AlwaysPreTouch
* @requires vm.gc.Parallel
* @requires os.maxMemory > 2G
* @requires !vm.debug
* @requires os.family == "linux"
* @library /test/lib
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx256m -Xms256m -XX:+UseParallelGC -XX:+AlwaysPreTouch gc.TestAlwaysPreTouchBehavior
*/
/**
* @test id=SerialCollector
* @summary tests AlwaysPreTouch
* @requires vm.gc.Serial
* @requires os.maxMemory > 2G
* @requires !vm.debug
* @requires os.family == "linux"
* @library /test/lib
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx256m -Xms256m -XX:+UseSerialGC -XX:+AlwaysPreTouch gc.TestAlwaysPreTouchBehavior
*/
/**
* @test id=Shenandoah
* @summary tests AlwaysPreTouch
* @requires vm.gc.Shenandoah
* @requires os.maxMemory > 2G
* @requires !vm.debug
* @requires os.family == "linux"
* @library /test/lib
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx256m -Xms256m -XX:+UseShenandoahGC -XX:+AlwaysPreTouch gc.TestAlwaysPreTouchBehavior
*/
/**
* @test id=G1
* @summary tests AlwaysPreTouch
* @requires vm.gc.G1
* @requires os.maxMemory > 2G
* @requires !vm.debug
* @requires os.family == "linux"
* @library /test/lib
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx256m -Xms256m -XX:+AlwaysPreTouch gc.TestAlwaysPreTouchBehavior
*/
/**
* @test id=Z
* @summary tests AlwaysPreTouch
* @requires vm.gc.Z
* @requires os.maxMemory > 2G
* @requires !vm.debug
* @requires os.family == "linux"
* @library /test/lib
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UseZGC -Xmx256m -Xms256m -XX:+AlwaysPreTouch gc.TestAlwaysPreTouchBehavior
*/
/**
* @test id=Epsilon
* @summary tests AlwaysPreTouch
* @requires vm.gc.Epsilon
* @requires os.maxMemory > 2G
* @requires !vm.debug
* @requires os.family == "linux"
* @library /test/lib
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC -Xmx256m -Xms256m -XX:+AlwaysPreTouch gc.TestAlwaysPreTouchBehavior
*/
import jdk.test.lib.Asserts;
import jdk.test.whitebox.WhiteBox;
import jtreg.SkippedException;
public class TestAlwaysPreTouchBehavior {
//
// This test tests the ability of the JVM to pretouch its java heap for test purposes (AlwaysPreTouch). We start a
// JVM with -XX:+AlwaysPreTouch, then observe RSS and expect to see RSS covering the entirety of the java heap,
// since it should all be pre-touched now.
//
// This test is important (we had pretouching break before) but very shaky since RSS of the JVM process is subject to
// host machine conditions. If there is memory pressure, we may swap parts of the heap out after pretouching and
// before measuring RSS, thus tainting the result.
//
// This test attempts to minimize the risk of false positives stemming from memory pressure by:
// - specifying @requires os.maxMemory > 2G
// - checking if the memory still available on the host machine after starting the process is lower than a
// certain required threshold; if it is, we take this as a sign of memory pressure and disregard test errors.
// - we only run this test with release JVMs - debug JVMs have a higher and more unpredictable RSS footprint
// and therefore would require a larger heap for a clear difference between non-pretouch and pretouch; also,
// there should not be much difference between debug and release code.
//
// Obviously, all of this is not bulletproof and only useful on Linux:
// - On MacOS, os::available_memory() drastically underreports available memory, so this technique would almost
// always fail to function
// - On AIX, we dont have a way to measure rss yet.
//
public static void main(String [] args) {
long rss = WhiteBox.getWhiteBox().rss();
System.out.println("RSS: " + rss);
long available = WhiteBox.getWhiteBox().hostAvailableMemory();
System.out.println("Host available memory: " + available);
long heapSize = 256 * 1024 * 1024;
// On Linux, a JVM that runs with 256M pre-committed heap will use about 60MB (release JVM) RSS. Barring
// memory pressure that causes us to lose RSS, pretouching should increase RSS to >256MB. So there should be a
// clear distinction between non-pretouched and pretouched.
long minRequiredRss = heapSize;
// The minimum required available memory size to count test errors as errors (to somewhat safely disregard
// outside memory pressure as the culprit). We are over-cautious and require at least 1G free. We rather err
// on the side of disregarding true errors than to produce false positives (if pretouching is broken, at least
// some of the runs of this test will run on beefy enough machines and show the test as failed).
long requiredAvailable = 1024 * 1024 * 1024;
if (rss == 0) {
throw new SkippedException("cannot get RSS?");
}
if (available > requiredAvailable) {
Asserts.assertGreaterThan(rss, minRequiredRss, "RSS of this process(" + rss + "b) should be bigger " +
"than or equal to heap size(" + heapSize + "b) (available memory: " + available + ")");
}
}
}
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