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From "Vladimir Strigun" <vstri...@gmail.com>
Subject Re: [classlib][java.math]performance improvement for java.math package
Date Tue, 20 Jun 2006 13:14:31 GMT
On 6/20/06, Mikhail Loenko <mloenko@gmail.com> wrote:
> I think they are not unit tests and should go to a different
> (performance?) test
> suite. Right now we don't have one but it seems to be time to create it

Of course, it's not unit tests, but my suggestion was based on our
testing convention.
What do you think about <modulename>/src/tests/performance ?

Thanks,
Vladimir.

> Thanks,
> Mikhail
>
> 2006/6/20, Vladimir Strigun <vstrigun@gmail.com>:
> > Hi Mikhail,
> >
> > AFAIK, we haven't such kind of tests in svn yet. It's hard to define
> > best place for it, but since this suite is intended for java.math
> > testing only and it's implementation-independent tests, I believe
> > modules/math/src/test/java/tests/api is appropriate place. If you
> > agree with this I will create patch for suite, add copyright and
> > change package definition of classes.
> >
> > What do you think about it?
> >
> > Thanks,
> > Vladimir.
> >
> > On 6/13/06, Mikhail Loenko <mloenko@gmail.com> wrote:
> > > Hi Vladimir
> > >
> > > What do you think the most appropriate location and suite for the tests
> > > in the HARMONY-551 are?
> > >
> > > Thanks,
> > > Mikhail
> > >
> > > 2006/6/2, Vladimir Strigun <vstrigun@gmail.com>:
> > > > Our team has done some analysis of current Harmony implementation of
> > > > java.math package. The implementation was considered from the
> > > > performance point of view and I'd like to share results of our work
> > > > with you.
> > > >
> > > > The analysis and tuning was made from the enterprise-level
> > > > applications point of view which are known to use BigInteger and
> > > > BigDecimal for storing numeric information. In most cases the numbers
> > > > there fit well within 32 bits. So coming from the BigDecimal
> > > > perspective which is really important for these applications and
> > > > taking into account some specifics (small numbers) we made some
> > > > optimizations in both BigDecimal and BigInteger. The latter was tuned
> > > > specifically for BigDecimal:
> > > >
> > > > - Special handling for small numbers (fit within 32 bit) was added to
> > > > all methods
> > > > - Frequently used constants (0..10) were cached and reused by valueOf
> > > > method (no need to create a new instance of BigInteger)
> > > > - as well as were powers of 10 (0..10)
> > > > - methods add(), divide(), divideAndRemainer() in BigInteger were
> > > > optimized for short values if both arguments can fit in 32 bits the
> > > > resulting BigInteger is created  by valueOf method.
> > > >
> > > >
> > > > If we consider enterprise level applications, we can imagine that
> > > > toString() method is also frequently used. The method was analyzed and
> > > > as a result we combined toString() methods in BigDecimal and
> > > > BigInteger to one unified method in BigInteger. Method
> > > > BigInteger.toDecimalScaledString(int scale) now  is used from  both
> > > > BigInteger and BigDecimal.  This way allows reducing amount of created
> > > > objects and data copying. In addition, size calculation was modified
> > > > for resulting array. In the new implementation the size is calculated
> > > > with less precision. Because allocated char array will be copied into
> > > > String and collected by GC after toString() then it is not a problem
> > > > if the allocated char array will be slightly bigger then necessary.
> > > >
> > > > I've attached the changes we made for BigInteger and BigDecimal to Harmony-551
> > > >
> > > > We also have created a set of micro benchmarks (which I'll to attach
> > > > to JIRA as well) which shows that our special-case handling doesn't
> > > > break the performance for other cases and we do not degrade in common,
> > > > and, of course, all unit tests pass with new version. Below you can
> > > > find several comparisons in performance between current version and
> > > > the fixed one.
> > > >
> > > > ===
> > > >
> > > > Ops/sec for toString() method of BigDecimal
> > > >
> > > > Number     Current       fixed one
> > > > of digits     version
> > > > 2       1121    5354
> > > > 4       774     7514
> > > > 8       615     6748
> > > > 12      743     5543
> > > > 16      623     4494
> > > > 24      389     4895
> > > > 32      306     3496
> > > > 48      232     5815
> > > > 64      224     3761
> > > > 128     91      87
> > > >
> > > > Ops/sec for divide method of BigInteger
> > > >
> > > > Number     Current       fixed one
> > > > of digits     version
> > > >
> > > > 2       5247    6315
> > > > 4       4623    6497
> > > > 8       5560    7491
> > > > 12      838     838
> > > > 16      2533    2063
> > > > 24      1689    1717
> > > > 32      2397    2494
> > > > 48      2143    2131
> > > > 64      613     525
> > > > 128     1399    1418
> > > >
> > > > Ops/sec for subtract method of BigInteger
> > > >
> > > > Number     Current       fixed one
> > > > of digits     version
> > > >
> > > > 2       3920    4394
> > > > 4       3300    3302
> > > > 8       5178    5640
> > > > 12      957     913
> > > > 16      3794    2904
> > > > 24      2057    1962
> > > > 32      3421    3241
> > > > 48      3469    2828
> > > > 64      652     610
> > > > 128     2318    2246
> > > >
> > > > ===
> > > >
> > > > Unfortunately we haven't look thoroughly to ITC contribution, so it
> > > > may happen that some of the optimizations described in this letter
> > > > were already implemented there. Daniel, could you please consider our
> > > > new implementation when you start to merge implementations math
> > > > packages. If optimization methods described above already have been
> > > > implemented in ITC contribution it will be great to compare internal
> > > > representation of BigInteger and try to measure affect of different
> > > > approaches.
> > > >
> > > >
> > > >
> > > >
> > > > On 6/2/06, Vladimir Strigun (JIRA) <jira@apache.org> wrote:
> > > > >     [ http://issues.apache.org/jira/browse/HARMONY-551?page=all ]
> > > > >
> > > > > Vladimir Strigun updated HARMONY-551:
> > > > > -------------------------------------
> > > > >
> > > > >    Attachment: Harmony-551.diffs
> > > > >
> > > > > Please try my patch.
> > > > > Several features were added:
> > > > > - special handling for small value
> > > > > - frequently used constans were cached
> > > > > - several methods were modified and optimized for small value.
> > > > > etc.
> > > > >
> > > > > > [classlib][java.math] performance improvement for java.math
package
> > > > > > -------------------------------------------------------------------
> > > > > >
> > > > > >          Key: HARMONY-551
> > > > > >          URL: http://issues.apache.org/jira/browse/HARMONY-551
> > > > > >      Project: Harmony
> > > > > >         Type: Improvement
> > > > >
> > > > > >   Components: Classlib
> > > > > >     Reporter: Vladimir Strigun
> > > > > >  Attachments: Harmony-551.diffs
> > > > > >
> > > > > > Performance improvement for BigDecimal and BigInteger classes.
> > > > > > I will attach patch soon.
> > > > >
> > > > > --
> > > > > This message is automatically generated by JIRA.
> > > > > -
> > > > > If you think it was sent incorrectly contact one of the administrators:
> > > > >   http://issues.apache.org/jira/secure/Administrators.jspa
> > > > > -
> > > > > For more information on JIRA, see:
> > > > >   http://www.atlassian.com/software/jira
> > > > >
> > > > >
> > > >
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