[Mono-dev] ToString() performace in Mono revisited

Sun Dec 30 20:58:38 EST 2007

Oops yes ;-)

BTW Kazuki cooked patches to reduce those memory usage with little
cost:

http://kserver.panicode.com/memo/2007/12/30/0
(327KB -> 57KB)

http://kserver.panicode.com/memo/2007/12/31/0
(57KB -> 20KB)

Atsushi Eno

Juraj Skripsky wrote:
> Hello,
> 
> I think the following two arrays account for most of those 300KB:
> 
> static readonly int[] _decHexDigits = new int [10000];
> static readonly int[] _decHexLen = new int [0x10000];
> 
> The first one consumes almost 40KB, the second one 256KB...
> 
> The "DblExpTab" array uses 2048 * 4 = 8KB and its referenced DblRep
> objects 2048 * (8 + 4 * 4) = 48KB. This means a total of 56KB. Turning
> DblExbTab into a struct would reduce this to 2048 * (4 * 4) = 32KB.
> 
> - Juraj
> 
> 
> On Mon, 2007-12-31 at 00:19 +0900, Atsushi Eno wrote:
>> Hello,
>>
>> Kazuki pointed out that the static initialization part of
>> NumberFormatter allocates 300KB. It is probably here:
>>
>> 	public static readonly DblRep[] DblExpTab = new DblRep [ExponentMax + 1];
>>
>> It does not look good.
>>
>> Atsushi Eno
>>
>>
>> Eyal Alaluf wrote:
>>>
>>> With the attchments zipped to reduce size.
>>>
>>>  
>>>
>>> * From: * mono-devel-list-bounces at lists.ximian.com 
>>> [mailto:mono-devel-list-bounces at lists.ximian.com] *On Behalf Of *Eyal Alaluf
>>> *Sent:* 27 December 2007 17:28
>>> *To:* mono-devel-list at lists.ximian.com
>>> *Cc:* Miguel de Icaza
>>> *Subject:* [Mono-dev] ToString() performace in Mono revisited
>>>
>>>  
>>>
>>> I got complaints that the font color within the table is white so this 
>>> is a resent J
>>>
>>>  
>>>
>>> Hi, all.
>>>
>>>  
>>>
>>> Attached is a redesigned implementation of the NumberFormatter class. 
>>> The patch includes a new algorithm for float and double ToString 
>>> implementation that improves performance by a factor of 25(!) and upto 
>>> 440(!!!). The patch includes further improvements to integer /ToString/ 
>>> as well as Andreas suggestion of avoiding calling 
>>> /NumberFormatInfo.CurrentInfo/ in the case of integer types default 
>>> /ToString()/ implementation.
>>>
>>> This patch should improve Mono’s performance in important use cases such 
>>> as web-services where primitive /ToString/ performance is an important 
>>> factor.
>>>
>>>  
>>>
>>> The following is a table showing the improvements for the different 
>>> primitive types using the patch. All the results are in milliseconds and 
>>> for a run of 10,000,000 iterations with warm-up of 10,000,000 iterations 
>>> as well.
>>>
>>>  
>>>
>>>  
>>>
>>> 	
>>>
>>> Mono 1.2.6
>>>
>>> 	
>>>
>>> Patch
>>>
>>> 	
>>>
>>> Improvement
>>>
>>> 12345.ToString(“G”)
>>>
>>> 	
>>>
>>> 10079
>>>
>>> 	
>>>
>>> 7328
>>>
>>> 	
>>>
>>> 1.37
>>>
>>> 12345L.ToString(“G”)
>>>
>>> 	
>>>
>>> 13203
>>>
>>> 	
>>>
>>> 7297
>>>
>>> 	
>>>
>>> 1.81
>>>
>>> 0.12345.ToString(“G”)
>>>
>>> 	
>>>
>>> 323750
>>>
>>> 	
>>>
>>> 13047
>>>
>>> 	
>>>
>>> 24.8(!)
>>>
>>> 1.2345E-200.ToString(“G”)
>>>
>>> 	
>>>
>>> 6376500
>>>
>>> 	
>>>
>>> 14328
>>>
>>> 	
>>>
>>> 445(!!!)
>>>
>>> 0.12345m.ToString(“G”)
>>>
>>> 	
>>>
>>> 51078
>>>
>>> 	
>>>
>>> 9875
>>>
>>> 	
>>>
>>> 5.2
>>>
>>> 12345.ToString()
>>>
>>> 	
>>>
>>> 12406/7781
>>>
>>> 	
>>>
>>> 5687
>>>
>>> 	
>>>
>>> 2.2/1.37
>>>
>>> 12345L.ToString()
>>>
>>> 	
>>>
>>> 15703/11016
>>>
>>> 	
>>>
>>> 5750
>>>
>>> 	
>>>
>>> 2.7/1.9
>>>
>>>  
>>>
>>> Note that for Mono 1.2.6 /12345/./ToString()/ there are two numbers – 
>>> the first is Mono 1.2.6 version (which is slower then 
>>> /12345.ToString(“G”)/!) and the second is after applying Andreas 
>>> suggestion on top of Mono 1.2.6.
>>>
>>>  
>>>
>>> The following are the results of the new algorithm compared to the old 
>>> Mono algorithm and the .Net 2.0 native ToString performance, all three 
>>> running on Microsoft .Net 2.0. The results show that the new code 
>>> matches and even out-performs .Net /ToString/ implementation.
>>>
>>>  
>>>
>>> 	
>>>
>>> Mono 1.2.6 algorithm
>>>
>>> 	
>>>
>>> Microsoft .Net 2.0
>>>
>>> 	
>>>
>>> New Patch algorithm
>>>
>>> 	
>>>
>>> Improvement over Mono 1.2.6
>>>
>>> 	
>>>
>>> Improvement over .Net 2.0
>>>
>>> 12345.ToString(“G”)
>>>
>>> 	
>>>
>>> 3700
>>>
>>> 	
>>>
>>> 2291
>>>
>>> 	
>>>
>>> 1827
>>>
>>> 	
>>>
>>> 2.0
>>>
>>> 	
>>>
>>> 1.25
>>>
>>> 12345L.ToString(“G”)
>>>
>>> 	
>>>
>>> 4559
>>>
>>> 	
>>>
>>> 2242
>>>
>>> 	
>>>
>>> 1919
>>>
>>> 	
>>>
>>> 2.38
>>>
>>> 	
>>>
>>> 1.17
>>>
>>> 0.12345.ToString(“G”)
>>>
>>> 	
>>>
>>> 281090
>>>
>>> 	
>>>
>>> 4006
>>>
>>> 	
>>>
>>> 3897
>>>
>>> 	
>>>
>>> 72.1(!!)
>>>
>>> 	
>>>
>>> 1.03
>>>
>>> 1.2345E-200.ToString(“G”)
>>>
>>> 	
>>>
>>> 5686000
>>>
>>> 	
>>>
>>> 4634
>>>
>>> 	
>>>
>>> 4613
>>>
>>> 	
>>>
>>> 1233(!!!)
>>>
>>> 	
>>>
>>> 1.00
>>>
>>> 0.12345m.ToString(“G”)
>>>
>>> 	
>>>
>>> 14562
>>>
>>> 	
>>>
>>> 3095
>>>
>>> 	
>>>
>>> 2294
>>>
>>> 	
>>>
>>> 6.3
>>>
>>> 	
>>>
>>> 1.35
>>>
>>> 12345.ToString()
>>>
>>> 	
>>>
>>> 3900/3002
>>>
>>> 	
>>>
>>> 2344
>>>
>>> 	
>>>
>>> 1313
>>>
>>> 	
>>>
>>> 3.0/2.3
>>>
>>> 	
>>>
>>> 1.79
>>>
>>> 12345L.ToString()
>>>
>>> 	
>>>
>>> 4684/3823
>>>
>>> 	
>>>
>>> 2245
>>>
>>> 	
>>>
>>> 1383
>>>
>>> 	
>>>
>>> 3.4/2.8
>>>
>>> 	
>>>
>>> 1.62
>>>
>>>  
>>>
>>> It should be noted that the new code performance improvement are even 
>>> more visible on top of .Net.
>>>
>>> It should also be noted that .Net runs the same algorithm 4 times faster 
>>> then Mono. Since this code is self contained and almost completely 
>>> algorithmic – I believe that it may serve as a good practical test case 
>>> for improving Mono’s JIT.
>>>
>>>  
>>>
>>> The redesign is composed of three main changes
>>>
>>> ·        An O(1) arithmetic transformation of a double (composed of 
>>> sign, 2’s exponent and mantissa bits) to sign, long and 10’s exponent.
>>>
>>> ·        Using a character array instead of a string buffer to construct 
>>> the string result.
>>>
>>> ·        Representing the number digits using hexadecimal values. That 
>>> is /12345/ will be represented by /0x12345/.
>>>
>>>  
>>>
>>> The patch passes Mono’s unit tests on both 1.1 and 2.0.
>>>
>>>  
>>>
>>> Please review and provide us with your feedback as soon as possible.
>>>
>>>  
>>>
>>> Sasha, Roei & Eyal.
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> Mono-devel-list mailing list
>>> Mono-devel-list at lists.ximian.com
>>> http://lists.ximian.com/mailman/listinfo/mono-devel-list
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