jdk-24/test/hotspot/jtreg/compiler/codecache/CheckLargePages.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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/*
 * @test
 * @bug 8304954
 * @summary Code cache reservation should gracefully downgrade to using smaller pages if the code cache size is too small to host the requested page size.
 * @requires os.family == "linux"
 * @requires vm.gc != "Z"
 * @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:+UseLargePages -XX:LargePageSizeInBytes=1g compiler.codecache.CheckLargePages
 */

package compiler.codecache;

import jdk.test.lib.Asserts;
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;
import jdk.test.whitebox.WhiteBox;
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

import java.util.Arrays;
import java.util.List;

public class CheckLargePages {
    private final static long LP_1G = 1024 * 1024 * 1024;
    private final static boolean LARGE_PAGES_ENABLED;
    private final static long LARGE_PAGE_SIZE;
    private final static String LARGE_PAGE_NUMBER_FILE_BASE = "/sys/kernel/mm/hugepages/hugepages-%skB/nr_hugepages";

    static {
        WhiteBox whiteBox = WhiteBox.getWhiteBox();
        LARGE_PAGES_ENABLED = whiteBox.getBooleanVMFlag("UseLargePages");
        LARGE_PAGE_SIZE = (whiteBox.getBooleanVMFlag("UseLargePages")) ? whiteBox.getVMLargePageSize() : 0;
    }

    private static boolean isLargePageSizeEqual(long size) {
        return LARGE_PAGE_SIZE == size;
    }

    private static int numberOfLargePages(long size) {
        String largePageNumberFile = String.format(LARGE_PAGE_NUMBER_FILE_BASE, size / 1024);
        try (Scanner scanner = new Scanner(new File(largePageNumberFile))) {
            if (scanner.hasNextInt()) {
                return scanner.nextInt();
            }
        } catch (FileNotFoundException e) { };
        return 0;
    }

    private static void testSegmented2GbCodeCacheWith1GbPage() throws Exception {
        ProcessBuilder pb = ProcessTools.createLimitedTestJavaProcessBuilder(
                "-XX:+UseLargePages",
                "-XX:+SegmentedCodeCache",
                "-XX:InitialCodeCacheSize=2g",
                "-XX:ReservedCodeCacheSize=2g",
                "-XX:LargePageSizeInBytes=1g",
                "-Xlog:pagesize=info",
                "-version");
        OutputAnalyzer out = new OutputAnalyzer(pb.start());
        out.shouldMatch("Code cache size too small for \\S* pages\\. Reverting to smaller page size \\((\\S*)\\)\\.");
        out.shouldHaveExitValue(0);
        // Parse page sizes to find next biggest page
        String sizes = out.firstMatch("Usable page sizes:([^.]+)", 1);
        List<Long> sizeList = Arrays.stream(sizes.trim().split("\\s*,\\s*")).map(CheckLargePages::parseMemoryString)
                .sorted().toList();
        final int smallerPageSizeIndex = sizeList.indexOf(LARGE_PAGE_SIZE) - 1;
        Asserts.assertGreaterThanOrEqual(smallerPageSizeIndex, 0);
        final long smallerPageSize = sizeList.get(smallerPageSizeIndex);
        // Retrieve reverted page size from code cache warning
        String revertedSizeString = out.firstMatch(
                "Code cache size too small for (\\S*) pages. Reverting to smaller page size \\((\\S*)\\)\\.", 2);
        Asserts.assertEquals(parseMemoryString(revertedSizeString), smallerPageSize);
    }

    private static void testDefaultCodeCacheWith1GbLargePages() throws Exception {
        ProcessBuilder pb = ProcessTools.createLimitedTestJavaProcessBuilder(
                "-XX:+UseLargePages",
                "-XX:LargePageSizeInBytes=1g",
                "-XX:+PrintCodeCache",
                "-version");
        OutputAnalyzer out = new OutputAnalyzer(pb.start());
        out.shouldHaveExitValue(0);
        out.shouldContain("CodeHeap 'non-nmethods'");
        out.shouldContain("CodeHeap 'profiled nmethods'");
        out.shouldContain("CodeHeap 'non-profiled nmethods'");
    }

    private static void testNonSegmented1GbCodeCacheWith1GbLargePages() throws Exception {
        ProcessBuilder pb = ProcessTools.createLimitedTestJavaProcessBuilder(
                "-XX:+UseLargePages",
                "-XX:LargePageSizeInBytes=1g",
                "-XX:ReservedCodeCacheSize=1g",
                "-XX:InitialCodeCacheSize=1g",
                "-XX:+PrintCodeCache",
                "-Xlog:pagesize=info",
                "-version");
        OutputAnalyzer out = new OutputAnalyzer(pb.start());
        out.shouldHaveExitValue(0);
        out.shouldNotContain("CodeHeap 'non-nmethods'");
        out.shouldNotContain("CodeHeap 'profiled nmethods'");
        out.shouldNotContain("CodeHeap 'non-profiled nmethods'");
        out.shouldContain("UseLargePages=1, UseTransparentHugePages=0");
        out.shouldMatch("CodeCache:  min=1[gG] max=1[gG] base=[^ ]+ size=1[gG] page_size=1[gG]");
    }

    public static void main(String[] args) throws Exception {
        if (isLargePageSizeEqual(LP_1G)) {
            testSegmented2GbCodeCacheWith1GbPage();
            if (numberOfLargePages(LP_1G) >= 1) {
                testDefaultCodeCacheWith1GbLargePages();
                testNonSegmented1GbCodeCacheWith1GbLargePages();
            } else {
                System.out.println("Skipping testDefaultCodeCacheWith1GbLargePages and " +
                        "testNonSegmented1GbCodeCacheWith1GbLargePages, no 1Gb pages available");
            }
        } else {
            System.out.println("1GB large pages not supported: UseLargePages=" + LARGE_PAGES_ENABLED +
                    (LARGE_PAGES_ENABLED ? ", largePageSize=" + LARGE_PAGE_SIZE : "") + ". Skipping");
        }
    }

    public static long parseMemoryString(String value) {
        value = value.toUpperCase();
        long multiplier = 1;
        if (value.endsWith("B")) {
            multiplier = 1;
        } else if (value.endsWith("K")) {
            multiplier = 1024;
        } else if (value.endsWith("M")) {
            multiplier = 1024 * 1024;
        } else if (value.endsWith("G")) {
            multiplier = 1024 * 1024 * 1024;
        } else {
            throw new IllegalArgumentException("Expected memory string '" + value + "'to end with either of: B, K, M, G");
        }

        long longValue = Long.parseUnsignedLong(value.substring(0, value.length() - 1));

        return longValue * multiplier;
    }
}