Serious performance problems (new snapshot has some performance improvement)

[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?


Gerrit
-- 
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