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8262188: Add test to verify trace page sizes logging on Linux
Reviewed-by: stuefe, tschatzl
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kstefanj committed Mar 1, 2021
1 parent 0a7fff4 commit fe8e3707c5ee0681aad1277bf03b2c7ef9ab0905
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/*
* Copyright (c) 2021, 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=no-options
* @summary Run test with no arguments apart from the ones required by
* the test.
* @requires os.family == "linux"
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log TestTracePageSizes
*/

/*
* @test id=explicit-large-page-size
* @summary Run test explicitly with both 2m and 1g pages on x64. Excluding ZGC since
* it fail initialization if no large pages are available on the system.
* @requires os.family == "linux"
* @requires os.arch=="amd64" | os.arch=="x86_64"
* @requires vm.gc != "Z"
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseLargePages -XX:LargePageSizeInBytes=2m TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseLargePages -XX:LargePageSizeInBytes=1g TestTracePageSizes
*/

/*
* @test id=compiler-options
* @summary Run test without segmented code cache. Excluding ZGC since it
* fail initialization if no large pages are available on the system.
* @requires os.family == "linux"
* @requires vm.gc != "Z"
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:-SegmentedCodeCache TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:-SegmentedCodeCache -XX:+UseLargePages TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:-SegmentedCodeCache -XX:+UseTransparentHugePages TestTracePageSizes
*/

/*
* @test id=with-G1
* @summary Run tests with G1
* @requires os.family == "linux"
* @requires vm.gc.G1
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseG1GC TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseG1GC -XX:+UseLargePages TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseG1GC -XX:+UseTransparentHugePages TestTracePageSizes
*/

/*
* @test id=with-Parallel
* @summary Run tests with Parallel
* @requires os.family == "linux"
* @requires vm.gc.Parallel
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseParallelGC TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseParallelGC -XX:+UseLargePages TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseParallelGC -XX:+UseTransparentHugePages TestTracePageSizes
*/

/*
* @test id=with-Serial
* @summary Run tests with Serial
* @requires os.family == "linux"
* @requires vm.gc.Serial
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseSerialGC TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseSerialGC -XX:+UseLargePages TestTracePageSizes
* @run main/othervm -XX:+AlwaysPreTouch -Xlog:pagesize:ps-%p.log -XX:+UseSerialGC -XX:+UseTransparentHugePages TestTracePageSizes
*/

import java.io.File;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

// Check that page sizes logged match what is recorded in /proc/self/smaps.
// For transparent huge pages the matching is best effort since we can't
// know for sure what the underlying page size is.
public class TestTracePageSizes {
// Store address ranges with known page size.
private static LinkedList<RangeWithPageSize> ranges = new LinkedList<>();
private static boolean debug;

// Parse /proc/self/smaps using a regexp capturing the address
// ranges, what page size they have and if they might use
// transparent huge pages. The pattern is not greedy and will
// match as little as possible so each "segment" in the file
// will generate a match.
private static void parseSmaps() throws Exception {
String smapsPatternString = "(\\w+)-(\\w+).*?" +
"KernelPageSize:\\s*(\\d*) kB.*?" +
"VmFlags: ([\\w ]*)";
Pattern smapsPattern = Pattern.compile(smapsPatternString, Pattern.DOTALL);
Scanner smapsScanner = new Scanner(new File("/proc/self/smaps"));
// Find all memory segments in the smaps-file.
smapsScanner.findAll(smapsPattern).forEach(mr -> {
String start = mr.group(1);
String end = mr.group(2);
String ps = mr.group(3);
String vmFlags = mr.group(4);

// Create a range given the match and add it to the list.
RangeWithPageSize range = new RangeWithPageSize(start, end, ps, vmFlags);
ranges.add(range);
debug("Added range: " + range);
});
smapsScanner.close();
}

// Search for a range including the given address.
private static RangeWithPageSize getRange(String addr) {
long laddr = Long.decode(addr);
for (RangeWithPageSize range : ranges) {
if (range.includes(laddr)) {
return range;
}
}
return null;
}

// Helper to get the page size in KB given a page size parsed
// from log_info(pagesize) output.
private static long pageSizeInKB(String pageSize) {
String value = pageSize.substring(0, pageSize.length()-1);
String unit = pageSize.substring(pageSize.length()-1);
long ret = Long.parseLong(value);
if (unit.equals("K")) {
return ret;
} else if (unit.equals("M")) {
return ret * 1024;
} else if (unit.equals("G")) {
return ret * 1024 * 1024;
}
return 0;
}

// The test needs to be run with:
// * -Xlog:pagesize:ps-%p.log - To generate the log file parsed
// by the test itself.
// * -XX:+AlwaysPreTouch - To make sure mapped memory is touched
// so the relevant information is recorded in the smaps-file.
public static void main(String args[]) throws Exception {
// Check if debug printing is enabled.
if (args.length > 0 && args[0].equals("-debug")) {
debug = true;
} else {
debug = false;
}

// Parse /proc/self/smaps to compare with values logged in the VM.
parseSmaps();

// Setup patters for the JVM page size logging.
String traceLinePatternString = ".*base=(0x[0-9A-Fa-f]*).*page_size=([^ ]+).*";
Pattern traceLinePattern = Pattern.compile(traceLinePatternString);

// The test needs to be run with page size logging printed to ps-$pid.log.
Scanner fileScanner = new Scanner(new File("./ps-" + ProcessHandle.current().pid() + ".log"));
while (fileScanner.hasNextLine()) {
String line = fileScanner.nextLine();
if (line.matches(traceLinePatternString)) {
Matcher trace = traceLinePattern.matcher(line);
trace.find();

String address = trace.group(1);
String pageSize = trace.group(2);

RangeWithPageSize range = getRange(address);
if (range == null) {
debug("Could not find range for: " + line);
throw new AssertionError("No memory range found for address: " + address);
}

long pageSizeFromSmaps = range.getPageSize();
long pageSizeFromTrace = pageSizeInKB(pageSize);

debug("From logfile: " + line);
debug("From smaps: " + range);

if (pageSizeFromSmaps != pageSizeFromTrace) {
if (pageSizeFromTrace > pageSizeFromSmaps && range.isTransparentHuge()) {
// Page sizes mismatch because we can't know what underlying page size will
// be used when THP is enabled. So this is not a failure.
debug("Success: " + pageSizeFromTrace + " > " + pageSizeFromSmaps + " and THP enabled");
} else {
debug("Failure: " + pageSizeFromSmaps + " != " + pageSizeFromTrace);
throw new AssertionError("Page sizes mismatch: " + pageSizeFromSmaps + " != " + pageSizeFromTrace);
}
} else {
debug("Success: " + pageSizeFromSmaps + " == " + pageSizeFromTrace);
}
}
debug("---");
}
fileScanner.close();
}

private static void debug(String str) {
if (debug) {
System.out.println(str);
}
}
}

// Class used to store information about memory ranges parsed
// from /proc/self/smaps. The file contain a lot of information
// about the different mappings done by an application, but the
// lines we care about are:
// 700000000-73ea00000 rw-p 00000000 00:00 0
// ...
// KernelPageSize: 4 kB
// ...
// VmFlags: rd wr mr mw me ac sd
//
// We use the VmFlags to know what kind of huge pages are used.
// For transparent huge pages the KernelPageSize field will not
// report the large page size.
class RangeWithPageSize {
private long start;
private long end;
private long pageSize;
private boolean vmFlagHG;
private boolean vmFlagHT;

public RangeWithPageSize(String start, String end, String pageSize, String vmFlags) {
this.start = Long.parseUnsignedLong(start, 16);
this.end = Long.parseUnsignedLong(end, 16);
this.pageSize = Long.parseLong(pageSize);

vmFlagHG = false;
vmFlagHT = false;
// Check if the vmFlags line include:
// * ht - Meaning the range is mapped using explicit huge pages.
// * hg - Meaning the range is madvised huge.
for (String flag : vmFlags.split(" ")) {
if (flag.equals("ht")) {
vmFlagHT = true;
} else if (flag.equals("hg")) {
vmFlagHG = true;
}
}
}

public long getPageSize() {
return pageSize;
}

public boolean isTransparentHuge() {
return vmFlagHG;
}

public boolean isExplicitHuge() {
return vmFlagHT;
}

public boolean includes(long addr) {
return start <= addr && addr < end;
}

public String toString() {
return "[" + Long.toHexString(start) + ", " + Long.toHexString(end) + ") " +
"pageSize=" + pageSize + "KB isTHP=" + vmFlagHG + " isHUGETLB=" + vmFlagHT;
}
}

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