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

[Atsushi Eno]

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.
> 
> 
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