Re: Code review request for 6908131 Pure Java implementations of StrictMath.floor(double) &StrictMath.ceil(double)

Thu, 21 Jan 2010 14:31:14 -0800 

A few comments.
First, part and parcel of doing numerical libraries work is developing tests; see, "Test where the failures are likely to be" (http://blogs.sun.com/darcy/entry/test_where_the_failures_are). An obvious set of tests to run are the regression tests I wrote as part of the fix for this bug (http://hg.openjdk.java.net/jdk7/jdk7/jdk/rev/ad1e30930c6c). 


Second, micro-benchmarking Java programs is a subtle art; see Cliff 
Click's various writeups for guidance, including


http://www.azulsystems.com/events/javaone_2002/microbenchmarks.pdf
http://blogs.azulsystems.com/cliff/2008/03/another-round-o.html
http://www.azulsystems.com/events/javaone_2009/session/2009_J1_Benchmark.pdf


Various benchmarks are examined by the performance team.  You can assume 
 benchmarks Sun publishes numbers on are included in the set of 
benchmarks of interest :-)


-Joe

Jeff Hain wrote:

 
Dmitry,
 
 From your bench, I see FloorCeil methods get in trouble

with 64 bits architecture, but I never ran anything on 64 bits yet.

I ran your bench on my laptop:
- DELL inspiron 9400, with (two) Genuine Intel T2300 @ 1.666GHz.
- java.runtime.version=1.6.0_11-b03
- java.class.version=50.0
- os.name=Windows XP
- os.arch=x86
- os..version=5.1

I added two patterns:
- pattern3 ("common" case (for doubles) of non-integer values) {
            0.1, -0.1,
        1e4+0.1, -1e4-0.1,
        1e8+0.1, -1e8-0.1,
       1e12+0.1, -1e12-0.1,
   (1L<<52)/1.1, -(1L<<52)/1.1}
- pattern4 (case of integer values) {
            0.0, -0.0,
            1e4, -1e4,
            1e8, -1e8,
       (1L<<52), -(1L<<52),
       (1L<<60), -(1L<<60)}


I also added test of the pure Java StrictMath class (which is the one 
you ran

as "StrictMath" in your bench?) posted on this subject: "StrictMath_JD".

Here is what I got:

 
-----------------------------------------

- CLIENT
-----------------------------------------

 
pattern 1:
empty                took       4,42 nsec 
Math.ceil            took      63,77 nsec 
Math.floor           took      67,55 nsec 
StrictMath.ceil      took      64,20 nsec 
StrictMath.floor     took      68,76 nsec 
StrictMath_JD.ceil   took      52,58 nsec 
StrictMath_JD.floor  took      53,57 nsec 
FloorCeil.ceil       took      24,31 nsec 
FloorCeil.floor      took      18,37 nsec 
 
pattern 2:

empty                took       4,50 nsec
Math.ceil            took     110,95 nsec
Math.floor           took     110,42 nsec
StrictMath.ceil      took     111,38 nsec
StrictMath.floor     took     110,97 nsec
StrictMath_JD.ceil   took      48,95 nsec
StrictMath_JD.floor  took      49,38 nsec
FloorCeil.ceil       took      23,29 nsec
FloorCeil.floor      took      20,81 nsec

 
pattern 3:

empty                took       4,39 nsec
Math.ceil            took     111,72 nsec
Math.floor           took     114,48 nsec
StrictMath.ceil      took     113,68 nsec
StrictMath.floor     took     114,32 nsec
StrictMath_JD.ceil   took      60,23 nsec
StrictMath_JD.floor  took      60,13 nsec
FloorCeil.ceil       took      27,11 nsec
FloorCeil.floor      took      23,77 nsec

 
pattern 4:

empty                took       4,38 nsec
Math.ceil            took     113,49 nsec
Math.floor           took     113,34 nsec
StrictMath.ceil      took     110,35 nsec
StrictMath.floor     took     112,95 nsec
StrictMath_JD.ceil   took      43,69 nsec
StrictMath_JD.floor  took      44,28 nsec
FloorCeil.ceil       took      22,09 nsec
FloorCeil.floor      took      18,71 nsec

 
-----------------------------------------

- SERVER
-----------------------------------------

 
pattern 1:
empty                took       2,40 nsec 
Math.ceil            took      64,61 nsec 
Math.floor           took      65,14 nsec 
StrictMath.ceil      took      63,93 nsec 
StrictMath.floor     took      65,99 nsec 
StrictMath_JD.ceil   took      37,52 nsec 
StrictMath_JD.floor  took      39,77 nsec 
FloorCeil.ceil       took      21,36 nsec 
FloorCeil.floor      took      13,96 nsec 
 
pattern 2:

empty                took       2,23 nsec
Math.ceil            took     112,42 nsec
Math.floor           took     110,88 nsec
StrictMath.ceil      took     112,05 nsec
StrictMath.floor     took     113,54 nsec
StrictMath_JD.ceil   took      33,98 nsec
StrictMath_JD.floor  took      33,97 nsec
FloorCeil.ceil       took      22,09 nsec
FloorCeil.floor      took      16,75 nsec

 
pattern 3:

empty                took       2,19 nsec
Math.ceil            took     113,67 nsec
Math.floor           took     113,53 nsec
StrictMath.ceil      took     114,46 nsec
StrictMath.floor     took     115,02 nsec
StrictMath_JD.ceil   took      44,19 nsec
StrictMath_JD.floor  took      43,57 nsec
FloorCeil.ceil       took      25,57 nsec
FloorCeil.floor      took      20,95 nsec

 
pattern 4:

empty                took       2,45 nsec
Math.ceil            took     108,56 nsec
Math.floor           took     112,96 nsec
StrictMath.ceil      took     109,43 nsec
StrictMath.floor     took     113,14 nsec
StrictMath_JD.ceil   took      30,18 nsec
StrictMath_JD.floor  took      31,07 nsec
FloorCeil.ceil       took      18,11 nsec
FloorCeil.floor      took      15,91 nsec

 
-----------------------------------------


Jeff

PS : The ceil and floor I posted here are an extract of a FastMath class 
(I already
     see some people in this mailing list invoking the gods against me 
while having
     a heart attack at the hearing of this class name) I did, and put on 
source
     forge (I already told about it in this list few months ago): maybe 
some of
     you might want to take a look at it (it's called "FastMath", but 
not ALL of

     its treatments are wrong...).

 


























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