A JVMTI agent to be used with microbenchmarks. Basic features:
- Reports major JVM events such as GC and JIT runs.
- Can collect performance counters through JNI.
- Can collect accurate time through JNI.
private static final int LOOPS = 10;
private static final String[] EVENTS = {
/* The most precise clock available. */
"SYS:wallclock-time",
/* Number of JIT compilation events. */
"JVM:compilations",
/* L1 cache misses (only Linux with PAPI). */
"PAPI:PAPI_L1_DCM"
};
public static void myBenchmark() {
/*
* We would have LOOPS measurements and we want to record these EVENTS.
*
* But we limit ourselves to supported events (i.e. in this case it
* would remove PAPI:PAPI_L1_DCM event if libpapi would not be available
* on the system.
*/
Benchmark.init(LOOPS, Measurement.filterSupportedEvents(EVENTS));
for (int i = 0; i < LOOPS; i++) {
/* Start the measurement. */
Benchmark.start();
/* Here goes your code that ought to be measured. */
/* Stop the measurement. */
Benchmark.stop();
}
/* Get the results (available as Iterable<long[]>). */
BenchmarkResults results = Benchmark.getResults();
/* Either print them in CSV (to be later processed)... */
BenchmarkResultsPrinter.toCsv(results, System.out);
/* ... or as a space-padded table. */
BenchmarkResultsPrinter.table(results, System.out);
}To run your program with our agent, add the ubench-agent.jar to
your classpath and start JVM with the C-agent:
-agentpath:libubench-agent.so (GNU/Linux)
or -agentpath:ubench-agent.dll (Windows).
A more generic interface Measurement is available if you wish to
bind the measurement to a specific thread or if you need to measure
more things at once (though internal limitations of Linux perf
subsystem may apply).
You will need recent version of Ant and GCC. Then simple
ant && ant test test-junit
shall compile the agent and run the built-in tests
(you might need to set JAVA_HOME if you have JDK in non-standard location).
You might also wish to execute
ant lib
to create a JAR with the agent class files (it also copies the C-agent to the same folder for easier use).
Package cz.cuni.mff.d3s.perf.demo contains a small demo: the MeasureHashing
class measures performance of a file hashing with Java built-in MD5.
Run it with
ant demo
to produce results that could look like this:
demo:
[java] SYS_WALLCLOCK JVM_COMPILATIO PAPI_TOT_INS PAPI_L1_DCM
[java] 1516055 9 5539366 107004
[java] 1082882 0 3994763 14362
[java] 983808 1 3690908 13472
[java] 258992 0 1551475 7049
[java] 69000 1 468639 1405
[java] 67542 0 470675 1296
...
<truncated>
...
[java] 67091 0 470675 1286
[java] 68760 1 469812 1295
[java] Hash is d41d8cd98f00b204e9800998ecf8427e.
To list supported events, run the ListEvents demo program or execute
ant list-events.
SYS:wallclock-time- The most precise clock available.
clock_gettime(CLOCK_MONOTONIC)on Linux,QueryPerformanceCounter()on Windows.
- The most precise clock available.
SYS:thread-time- CPU thread time (i.e. not counting when thread is waiting).
SYS:thread-time-rusage- Same as
SYS:thread-timebut uses data fromgetrusage()call on Linux. Seems to be much less precise but it may save you one extra call if you also querySYS:forced-context-switches. Linux only.
- Same as
SYS:forced-context-switches- Number of forced context switches (i.e. quantum was exhausted). Linux only.
JVM:compilations- Number of JIT compilation events.
PAPI:*- When built on Linux with libpapi available, the agent can collect any
event supported by PAPI (note that you can use all the events reported
by
papi_availandpapi_native_avail). - Note that to use different components (e.g.
perfandrapl), different event sets has to be created.
- When built on Linux with libpapi available, the agent can collect any
event supported by PAPI (note that you can use all the events reported
by
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