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From "Aleksey Shipilev" <aleksey.shipi...@gmail.com>
Subject Re: [jira] Commented: (HARMONY-6056) [classlib][jit][opt][performance] Optimize heap allocations in String(String, int) constructor for JIT
Date Thu, 08 Jan 2009 12:46:41 GMT
Hi Jim, Kevin,

There are good things in both patches: Jim's one does the tricky
lookup for big integers, which benefit for them; Kevin's one does
division very cheaply.

I had tried several implementations of radix-10 Integer.toString():
 - (original) baseline, present in trunk
 - (kevin) Kevin's original one from HARMONY-6056
 - (kevin-aleksey) Kevin's one + guessing the buffer size
 - (jim) Jim's one from HARMONY-6068
 - (jim-aleksey) Jim's one + optimized division for small integers

The merged patch is attached to
https://issues.apache.org/jira/browse/HARMONY-6068.

The results are below. In short, Jim's patch rocks! :) It rocks even
more on small integers with Kevin's ideas. The best one is
"jim-aleksey", but it's too heavy to just copy-paste to String(String,
int) constructor, so there's a need in in-place Integer.toString()
conversion.

What do you think?

--------
(ops/msec, the more the better)

original-1024Mb:
*3969, 2612, 1944, 1481, 1168,
3831, 2557, 1906, 1447, 1153,
3692, 2635, 1971, 1495, 1186,
3914, 2626, 1958, 1482, 1170,
3947, 2630, 1961, 1478, 1179,

kevin-1024Mb:
5041, 3343, 2484, 1883, 1566,
5010, 3329, 2454, 1907, 1543,
5009, 3325, 2473, 1886, 1539,
4969, 3314, 2450, 1884, 1549,
4901, 3271, 2457, 1868, 1542,

kevin-aleksey-1024Mb:
5041, 4043, 3364, 2867, 2340,
5010, 3962, 3368, 2852, 2333,
4993, 3992, 3318, 2857, 2303,
4953, 3997, 3318, 2847, 2313,
4946, 3947, 3311, 2841, 2303,

jim-1024Mb:
4681, 3566, 3019, 2976, 2897,
4810, 3558, 3054, 2954, 2880,
4802, 3530, 2982, 2943, 2868,
4795, 3481, 2991, 2918, 2862,
4744, 3476, 2954, 2902, 2849,

jim-aleksey-1024Mb:
5041, 3977, 2919, 2964, 2860,
5066, 3918, 2951, 2929, 2873,
5090, 3918, 2886, 2920, 2875,
5018, 3918, 2938, 2934, 2878,
4978, 3917, 2921, 2868, 2831,


Thanks,
Aleksey.

On Thu, Jan 8, 2009 at 1:11 PM, Jim Yu <junjie0122@gmail.com> wrote:
> Thanks Aleksey! I think my patch is a general solution for this case and has
> no dependency on any optimized feature of J9 VM : )
> 2009/1/8 Aleksey Shipilev <aleksey.shipilev@gmail.com>
>
>> That's awesome, Jim!
>> Thanks for coming in :)
>>
>> However, you seem to be missing the point. I was talking about
>> refactoring Kevin's patch to fit the stated requirements. This is
>> merely because Kevin claim the patch already gives the boost for
>> SPECjbb2005. Kevin already has the specialized conversion in
>> String(String, int) private constructor.
>>
>> Nevertheless, your specialized version looks good with regards to
>> performance numbers, we need to test what's better for radix-10
>> conversion: Jim's version or Kevin's one now.
>>
>> Thanks a lot,
>> Aleksey.
>>
>> On Thu, Jan 8, 2009 at 12:11 PM, Jim Yu <junjie0122@gmail.com> wrote:
>> > Hi Aleksey,
>> > I very agree with you and I have implemented an optimized algorithm for
>> > Integer.toString(int) method. Thanks to your benchmark, here are the test
>> > results[1] on my windows platform.  I've raised a JIRA at
>> > https://issues.apache.org/jira/browse/HARMONY-6068
>> > [1]
>> > Result for Harmony java6 branch:
>> > (String)base + (int)add:
>> > -------------------------------------------
>> >  base length (vars with rows): 0..2..10
>> >  add length (vars with cols): 0..2..10
>> >
>> >  loop duration = 100 msecs
>> >  target variance = 0.05
>> >
>> > ops/msec, the more the better:
>> > 6721, 6096, *4650, *3846, *3178,
>> > *8080, *5833, *4447, 3731, 3048,
>> > *7985, *5848, 4788, 3727, *3114,
>> > *7891, 5592, *4389, *3560, 3048,
>> > 8388, 5607, *4522, 3727, 3051,
>> >
>> > After applied my patch:
>> > (String)base + (int)add:
>> > -------------------------------------------
>> >  base length (vars with rows): 0..2..10
>> >  add length (vars with cols): 0..2..10
>> >
>> >  loop duration = 100 msecs
>> >  target variance = 0.05
>> >
>> > ops/msec, the more the better:
>> > 8322, 6721, 4791, 4788, 4788,
>> > 8388, 6721, 5156, *5012, 4797,
>> > 8388, 6707, 5161, *4963, 4795,
>> > 8388, 6707, *5126, 4802, 4788,
>> > *8048, 6700, *5021, 4802, *4687,
>> >
>> > 2009/1/7 Aleksey Shipilev <aleksey.shipilev@gmail.com>
>> >
>> >> Ok, we can implement the in-place Integer.toString() and specialize
>> >> the radix-10 conversion in Integer. Then Classlib performance guys
>> >> might use the inplace conversion to optimize StringBuilder performance
>> >> or even catch the concatenation like J9 does.
>> >>
>> >> My idea is to share whatever optimization between all VMs that use the
>> >> Classlib.
>> >>
>> >> Thanks,
>> >> Aleksey.
>> >>
>> >> On Wed, Jan 7, 2009 at 5:46 PM, Tim Ellison <t.p.ellison@gmail.com>
>> wrote:
>> >> > Aleksey Shipilev wrote:
>> >> >> Am I understanding right that private String(String, int) is inlined
>> >> >> by J9 JIT when (String)s1 + (int)v1 is required?
>> >> >
>> >> > Yes - so for DRLVM, Kevin's patch in HARMONY-6056 will be impotent.
>> >> >
>> >> > Regards,
>> >> > Tim
>> >> >
>> >> >
>> >>
>> >
>> >
>> >
>> > --
>> > Best Regards,
>> > Jim, Jun Jie Yu
>> >
>> > China Software Development Lab, IBM
>> >
>>
>
>
>
> --
> Best Regards,
> Jim, Jun Jie Yu
>
> China Software Development Lab, IBM
>

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