Re: [Boost-bugs] [Boost C++ Libraries] #3218: string_algo algorithms are quite slow in some popular compiler/OS/hardware situations

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3218: string_algo algorithms are quite slow in some popular compiler/OS/hardware situations
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-06-26 22:30:43

#3218: string_algo algorithms are quite slow in some popular compiler/OS/hardware
situations
------------------------------------------------------+---------------------
 Reporter:  Yuri Goldfeld <yuri_goldfeld@…>           |       Owner:  pavol_droba
     Type:  Bugs                                      |      Status:  new        
Milestone:  To Be Determined                          |   Component:  string_algo
  Version:  Boost 1.37.0                              |    Severity:  Problem    
 Keywords:  performance string_algo strings           |  
------------------------------------------------------+---------------------

Comment(by anonymous):

 Good guess, especially since it seems like in-place-modifying functions
 like to_lower() are much slower than intuitively slower copying ones like
 to_lower_copy().  Unfortunately, disabling SCL did not fix it.  The 2nd
 perf.cpp I attached prints whether _SECURE_SCL is enabled in Windows.  I
 disabled it in Project Properties like you said (_SECURE_SCL=0).  I also
 turned up every optimization setting to maximum, with the resulting
 command line:

 {{{/Ox /Ob2 /Oi /Ot /Oy /GL /I "C:\workspaces\client-1.4.7\akamai\boost"
 /D "WIN32" /D "NDEBUG" /D "_CONSOLE" /D "_SECURE_SCL=0" /D "_UNICODE" /D
 "UNICODE" /FD /EHsc /MD /Gy /Fo"Release\\" /Fd"Release\vc90.pdb" /W3 /WX
 /nologo /c /Zi /TP /errorReport:prompt}}}


 This was the output:

 {{{
 C:\projects\boost_perf\Release>boost_perf.exe
 Windows build: _SECURE_SCL = 0
 string("abcdefgh") == string("abcdefgh")| 612 msec.
 equals(string("abcdefgh"), string("abcdefgh"))| 1046 msec.
 Boost/hand ratio = 1.70915

 StartsWith(string("abcdefghi"), "abcd")| 266 msec.
 starts_with(string("abcdefghi"), "abcd")| 553 msec.
 Boost/hand ratio = 2.07895

 StartsWithI(string("abcdefghi"), "aBcD")| 337 msec.
 istarts_with(string("abcdefghi"), "aBcD")| 3320 msec.
 Boost/hand ratio = 9.85163

 EqualsI("abcdefghi", "aBcDeFgHi")| 170 msec.
 iequals("abcdefghi", "aBcDeFgHi")| 5248 msec.
 Boost/hand ratio = 30.8706

 ToUpperCopy(string("aBcDeFgHi"))| 590 msec.
 to_upper_copy(string("aBcDeFgHi"))| 3445 msec.
 Boost/hand ratio = 5.83898

 ToLowerCopy(string("aBcDeFgHi"))| 591 msec.
 to_lower_copy(string("aBcDeFgHi"))| 3385 msec.
 Boost/hand ratio = 5.72758

 ToLower(str)| 160 msec.
 to_lower(str)| 2847 msec.
 Boost/hand ratio = 17.7938

 ToUpper(str)| 160 msec.
 to_upper(str)| 2841 msec.
 Boost/hand ratio = 17.7563
 }}}

 Note the first line, which prints the value of _SECURE_SCL.  The docs you
 gave were for VS 2005, but it's all the same for VS 2008:
 http://msdn.microsoft.com/en-us/library/aa985965.aspx


 If there's anything else to try, let me know.

 Replying to [comment:2 pavol_droba]:
 > Just curious,  VC++2008 employs quite rigorous run-time checking, which
 is sometimes enabled even in the Release mode. This checks significantly
 reduce the performance. To get a serious reading I suggest to disable all
 checks and compile in Relaase mode with maximum optimization possible. One
 example is SCL to disable it use #define _SECURE_SCL=0 or add
 _SECURE_SCL=0 into C++/Preprocessor in the project settings.
 >
 > Can you please re-run the tests using this settings?
 >
 > More info here:
 > http://msdn.microsoft.com/en-us/library/aa985965(VS.80).aspx

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3218#comment:3>
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