How to query the high-resolution performance counter

Question

Good morning,

i need to obtain the value of the CPUs high-resolution performance counter in order to measure delay between various software applications. In my c(++|#) i use the

BOOL WINAPI QueryPerformanceCounter( __out LARGE_INTEGER *lpPerformanceCount );

WinApi call. What is the proper way to obtain the counter from java. I have search jna without success. I know this is a platform specific issue, but maybe there is a quicker way than writing my own jni wrapper?

Best wishes, Armin

Jörn Horstmann · Accepted Answer · 2012-08-05 19:35:48Z

4

How about using System.nanoTime? I think that already uses the performance counters of the machine and there is no need to write a native wrapper.

Update: According to this article on clocks and timers in the jvm in the section "Clocks and Timers on Windows"

System.nanoTime() is implemented using the QueryPerformanceCounter/QueryPerformanceFrequency API

edited Aug 5, 2012 at 19:35

answered Apr 30, 2012 at 9:41

Jörn Horstmann

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5 Comments

armin o Over a year ago

Jörn, nanoTime() returns the time, rather than the uncooked performance counter. Since i want to measure delay between different applications i need the performance counter value rather than a transform.

Stas Over a year ago

nanoTime returns counter, not time. Read javadoc.

Motomotes Over a year ago

@Stas No, it returns the number of seconds the PC has been running, read the implementation: hg.openjdk.java.net/jdk8u/jdk8u/hotspot/file/0cd040567d60/src/…

Stas Over a year ago

@Motes "QueryPerformanceCounter" doesn't look like has anything with seconds. And "QueryPerformanceFrequency" which used to define "has_performance_count" has the following on MSDN: "On systems that run Windows XP or later, the function will always succeed and will thus never return zero.", which means that has_performance_count is always true.

Motomotes Over a year ago

The code returns jlong time = (jlong)((current/freq) * NANOSECS_PER_SEC);

Necrolis · Accepted Answer · 2012-06-04 10:23:50Z

Here is the native wrapper code

1) File W32Call.java

package jmSense.Native; public class W32Call { public native static long QueryPerformanceCounter( ); public native static int QueryPerformanceCounterInt32( );

2) run java h to create the include file

3) Create a dll "My Native Extensions.dll" from

#include "stdafx.h" #include "windows.h" #include "jmSense_Native_W32Call.h" JNIEXPORT jlong JNICALL Java_jmSense_Native_W32Call_QueryPerformanceCounter(JNIEnv *, jclass) { LARGE_INTEGER g_CurentCount; QueryPerformanceCounter((LARGE_INTEGER*)&g_CurentCount); return g_CurentCount.QuadPart; } JNIEXPORT jint JNICALL Java_jmSense_Native_W32Call_QueryPerformanceCounterInt32(JNIEnv *, jclass) { LARGE_INTEGER g_CurentCount; QueryPerformanceCounter((LARGE_INTEGER*)&g_CurentCount); return g_CurentCount.LowPart; }

4) Use it like this:

System.loadLibrary("My Native Extensions"); System.out.println(W32Call.QueryPerformanceCounter());

fine

Why would you do all that? QueryPerformanceCounter is used by System.nanoTime anyway. Just use System.nanoTime.

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