Re: Serious performance problems (new snapshot has some performance improvement)

[ralf dot habacker at freenet dot de]

Am Montag, 30. Mai 2005 22:33 schrieb Gerrit P. Haase:
> Anonymous wrote:
> 
> > My System:
> > #Set-up:
> > 
> > $ g++ cygspd.cc -o cygspd-basic
> > $ g++ -O7 cygspd.cc -o cygspd-o7
> > $ g++ -fno-exceptions cygspd.cc -o cygspd-ne
> > $ g++ -O7 -fno-exceptions cygspd.cc -o cygspd-ne-o7
> > $ g++ -mno-cygwin cygspd.cc -o cygspd-mingw
> > $ g++ -O7 -mno-cygwin cygspd.cc -o cygspd-mingw-o7
> > $ g++ -fno-exceptions -mno-cygwin cygspd.cc -o cygspd-mingw-ne
> > $ g++ -O7 -fno-exceptions -mno-cygwin cygspd.cc -o cygspd-mingw-ne-o7
> > 
> > # cygwin.dll 1.5.17
> [...]
> > $ /bin/time -f "%E %S %U" cygspd-mingw cygspd.dat
> > 0:03.11 0.00 0.02
> > $ /bin/time -f "%E %S %U" cygspd-mingw-o7 cygspd.dat
> > 0:01.50 0.01 0.02
> > $ /bin/time -f "%E %S %U" cygspd-mingw-ne cygspd.dat
> > 0:02.60 0.00 0.02
> > $ /bin/time -f "%E %S %U" cygspd-mingw-ne-o7 cygspd.dat
> > 0:01.50 0.01 0.01
> > 
> > #Snapshot DLL (No changes were made except swapping the dll.
> [...]
> > $ /bin/time -f "%E %S %U" cygspd-mingw cygspd.dat
> > 0:02.78 0.00 0.01
> > $ /bin/time -f "%E %S %U" cygspd-mingw-o7 cygspd.dat
> > 0:01.51 0.01 0.01
> > $ /bin/time -f "%E %S %U" cygspd-mingw-ne cygspd.dat
> > 0:02.52 0.00 0.02
> > $ /bin/time -f "%E %S %U" cygspd-mingw-ne-o7 cygspd.dat
> > 0:01.45 0.00 0.01
> 
> Interesting, why is it faster when running a binary that doesn't
> depend on cygwin1.dll after swapping the DLL?  Some Win caching mechanism?

I recognized this caching behavior with KDE/cygwin too. Under  
http://cvs.sourceforge.net/viewcvs.py/kde-cygwin/tools/fillmem/ there is a 
tool, which could be used to minimize this influcence by clearing this cache. 
See the README for more informations. 

Ralf  

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