hg: jdk7/tl/jdk: 6642323: Speeding up Single Byte Decoders; ...

[Ulf Zibis]

one more question, just for interest:
Can you see any performance difference between
    sp != sl
and
    sp < sl
?

-Ulf


Am 15.12.2008 23:19, Xueming Shen schrieb:
>
> The gain from doing
>
> int sr = src.remaining();
> int dr = dst.remaining();
>
> Ulf, thanks for looking into the changes.
>
> It might not be a good idea to skip the temporary variable c in the 
> loop, I'm not sure
> it's a good idea to put an "un-mappable" char into the output buffer 
> in case we have
> a un-mappable though yes we don't not change the buffer position. This 
> actually is
> all most all the gain come from in -server vm case when I run my 
> benchmark.
>
> However in "client" vm case, interestingly I do see some performance 
> gain with
> your proposed change, though I'm not sure why the loop gets faster 
> with a quick
> look. So I have created a new Cr #6785335 to keep trace this issue. 
> Will consider
> put this one into 7 later.
>
> Thanks again!
>
> Sherman
>
>
> Ulf Zibis wrote:
>> Maybe:
>>          for (int sl = sp + (sr <= dr ? sr : dr); sp != sl; sp++, dp++)
>> is little more faster than:
>>          for (int sl = sp + (sr <= dr ? sr : dr); sp < sl; sp++, dp++)
>>
>> -Ulf
>>
>>
>> Am 15.12.2008 21:56, Ulf Zibis schrieb:
>>> Maybe little faster, especially for short strings:
>>>
>>>       private CoderResult decodeArrayLoop(ByteBuffer src, CharBuffer 
>>> dst) {
>>>           byte[] sa = src.array();
>>>           int sp = src.arrayOffset() + src.position();
>>>           int sr = src.remaining();  // faster than ... 
>>> src.arrayOffset() + src.limit()
>>>
>>>           char[] da = dst.array();
>>>           int dp = dst.arrayOffset() + dst.position();
>>>           int dr = dst.remaining(); // dl is never used
>>>
>>>           for (int sl = sp + (sr <= dr ? sr : dr); sp < sl; sp++, dp++)
>>>               if ((da[dp] = decode(sa[sp])) == UNMAPPABLE_DECODING)
>>>                   return 
>>> withResult(CoderResult.unmappableForLength(1), src, sp, dst, dp);
>>>           return withResult(sr <= dr ? CoderResult.UNDERFLOW : 
>>> CoderResult.OVERFLOW, src, sp, dst, dp);
>>>       }
>>>
>>> Regards,
>>> Ulf
>>>
>>
>
>