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From "Vladimir Strigun" <vstri...@gmail.com>
Subject [classlib][performance] performance improvement for luni and nio_char modules - Harmony-1980
Date Thu, 26 Oct 2006 14:44:52 GMT
The optimization covers the following issues:
- java.nio.charset.CharsetDecoder and java.nio.charset.CharsetEncoder
Streaming decoding/encoding was removed. Analysis of API hotspots for
Dacapo shows that CharsetDecoder is frequently used almost in all
benchmark, especially in chart. We already discussed advantages of
streaming decoding but the fix shows significant performance
improvement on average for all Dacapo benchmarks. For instance, boost
for chart benchmark is about 16%. Paulex, you recently worked in
nio_char module and if I correctly remember you introduce streaming
operations, so could you please review the changes and let me know?
Since streaming operation was removed, tests have been slightly
modified as well (previous version of tests fails on RI).
- java.io.BufferedReader
readLine() method was slightly modified. Additional check whether some
characters available in cached buffer was added prior to main cycle.
- java.io.InputStreamReader
Cached char buffer was removed, read() , read(char[], int, int)
methods were rewritten. Current implementation of read(char[], int,
int) uses several invocation of System.arraycopy. Proposed solution
wraps char[] arguments within char buffer and therefore doesn't use
arraycopy. Decoding operation is also produced inside the method, so
fillBuf() has been removed

Thoughts? Comments?

Thanks,
Vladimir.

On 10/26/06, Vladimir Strigun (JIRA) <jira@apache.org> wrote:
> [classlib][performance] performance improvement for luni and nio_char modules
> -----------------------------------------------------------------------------
>
>                 Key: HARMONY-1980
>                 URL: http://issues.apache.org/jira/browse/HARMONY-1980
>             Project: Harmony
>          Issue Type: Improvement
>          Components: Classlib
>            Reporter: Vladimir Strigun
>         Attachments: Harmony-1980.diff
>
> I've analyzed API frequently used in all Dacapo[1] benchmarks and found several places
in luni and nio_char modules that can be improved. Suggested fix gives about 10-15% boost
on average for Dacapo executed on DRLVM. I'll post more details to dev list.
> Attached fix contains modifications for the following classes: java.io.BufferedReader,
java.io.InputStreamReader, java.nio.charset.CharsetDecoder and java.nio.charset.CharsetEncoder.
>
> Please have a look to the results of Dacapo execution (values are in millisec, so the
less the better):
>
> Small workload
>
>        OrigBuild   Patched
> bloat   996,078 1024,85
> chart   1240,777        1068,112
> fop     250,433 232,957
> hsqldb  348,942 361,139
> jython  831,143 824,775
> lusearch        1854,95 1870,969
> luindex 339,45  231,314
> pmd     29,704  23,638
>
>
> default workload
>        OrigBuild   Patched
> bloat   168733,562      175493,467
> chart   31651,792       25681,751
> fop     2546,289        2512,045
> hsqldb  22873,608       13555,515
> jython  128207,303      92863,28
> lusearch        29425,991       30064,153
> luindex 17825,795       18083,898
> pmd     44548,724       40225,694
>
>
>
> [1] http://dacapobench.sourceforge.net
>
>
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