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| When you find a bug in a compiler (like the DMD compiler) and you submit the bug, you are usually encouraged to give the smaller and simpler program (often just about 5 lines long) that shows the same problem/bug. This helps locate the problem, and remove it faster. At the same way microbenchmarks too can be useful, despite being so little they can't really represent what goes on in normal sized programs. They can show you in the simpler way what's better to improve. This tiny benchmark focus on GC performance and shows similar results to the "binary trees" benchmark I have shown here few weeks ago, but it's quite shorter, so it may be more useful. This code isn't meant to represent normal programs with thousands of classes, etc, it just shows something quite limited. This is an adaptation of the "Object Test" that you can find used and discussed here: http://www.twistedmatrix.com/users/glyp http://blog.snaplogic.org/?p=55 http://programming.reddit.com/info/24yn Note that I test the GC of Phobos only, I don't use Tango yet. Object Test timings (on PIII @ 500 MHz), best of 3 runs (seconds, approximate Mbytes memory used), n=1_000, m=10_000:
seconds MB
DMD class: 18.95 1.7
GDC class: 17.91 1.8
DMD struct: 11.77 1.7
GDC struct: 12.31 1.8
Python: 37.10 3.1 (ShedSkin version)
Psyco: 15.68 3.5
ShedSkin 6.35 1.6
Java (1): 2.19 7.3
Java (2): 2.10 7.8
See below for the sources. You can see the Java is about 9 (~= 18.95 / 2.10) times faster than the program produced by DMD. Even Psyco (the JIT for the turtle-slow language Python) gives faster performance (and the Python GC is simple, it's just a reference count plus cycle detection). You can also see Java (as usual) uses much more RAM (7.8/1.7 ~= 4.6). Note that with some manual GC optimization the running time for the DMD class benchmark can become about one-two seconds smaller, but the memory used can be about 4 MB:
import std.gc;
class ObjectTest { ObjectTest next; }
void main() {
for (uint k = 0; k < 50; k++) {
std.gc.disable();
for (uint i = 0; i < 20; i++) {
auto root = new ObjectTest();
for (uint j = 0; j < 10_000; j++) {
root.next = new ObjectTest();
root = root.next;
}
}
std.gc.fullCollect();
}
}
-------------------
COMPILED/RUN WITH: gcc version 3.4.5 (mingw special) (gdc 0.24, using dmd 1.020) DMD v1.024 javac 1.6.0_03 java version "1.6.0_03" Python 2.5.1 ShedSkin 0.0.25 (shedskin.sourceforge.net , a Python to C++ compiler) ------------------- COMPILATION/RUNNING PARAMETERS: GDC used as: gdc -O3 -s -frelease -finline-functions -ffast-math -fomit-frame-pointer -funroll-loops -march=pentiumpro obj_test_class.d -o obj_test_class_gdc DMD used as: dmd -O -release -inline obj_test_class.d -ofobj_test_class_dmd.exe Java compiled with: javac ObjectTest.java Java (1) run with: java ObjectTest Java (2) run with: java -Xms20m -Xbatch ObjectTest SS and Psyco compiled and run without flags.
-------------------
SOURCES:
// obj_test_class.d
class ObjectTest { ObjectTest next; }
void main() {
for (uint i = 0; i < 1_000; i++) {
auto root = new ObjectTest();
for (uint j = 0; j < 10_000; j++) {
root.next = new ObjectTest();
root = root.next;
}
}
}
-------------------
// obj_test_struct.d
struct ObjectTest { ObjectTest* next; }
void main() {
for (uint i = 0; i < 1_000; i++) {
auto root = new ObjectTest();
for (uint j = 0; j < 10_000; j++) {
root.next = new ObjectTest();
root = root.next;
}
}
}
-------------------
// ObjectTest.java
public class ObjectTest {
public ObjectTest next;
public static void main(String[] args) {
for (int i = 0; i < 1000; i++) {
ObjectTest root = new ObjectTest();
for (int j = 0; j < 10000; j++) {
root.next = new ObjectTest();
root = root.next;
}
}
}
}
Note that the HotSpot Java compiler FAQ warns to not use code like that: http://java.sun.com/docs/hotspot/HotSpo >if you insist on using/writing microbenchmarks like this, you can work around the problem by moving the body of main to a new method and calling it once from main to give the compiler a chance to compile the code, then calling it again in the timing bracket to see how fast HotSpot is.<
-------------------
# obj_test.py
from psyco.classes import __metaclass__
class ObjectTest: pass
def main():
for i in xrange(1000): # N
root = ObjectTest()
for j in xrange(10000): # M
root.next = ObjectTest()
root = root.next
import psyco; psyco.full()
main()
-------------------
# obj_test_ss.py
class ObjectTest: pass
def main():
for i in xrange(1000): # N
root = ObjectTest()
for j in xrange(10000): # M
root.next = ObjectTest()
root = root.next
main()
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comments: Leave a comment   |
leonardo
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December 11th, 2007
August 5th, 2006
leonardo
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