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fir

program start-up time optimization (and measuring)

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Some time ago I was trying to measure a start-up time of my c programs, I mean the exact time between the moment of running a program (from console or from gui shell) and the time where first 'commands' in my main() function are executed.

 

Then I do not find a convenient way of doing that it windows. The exact time of running my commands is no problem (QueryPerformanceCounter) but I do not found the way of getting the  exact time where program received a command to run (from within this program - and  that exact time is need for me, I mean the time before even program image and dlls are loaded - becouse this time is physical, stright related to delay of running my game and that is what I would like care to optymise)

 

Could someone help with that? (Does other systems (linux/mac)  have such problem with that I found on windows :/ ) ?

 

The second part of this question - what I could do to hard optymize this startup time, I think that lowering the size of images needed to be load by loader may count (it is exe size and sizes of ar dlls it depends on) but what else?

 

thanx fot the answer

Edited by fir

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If you want to measure all factors, such as loading the EXE file into RAM, etc, then you won't be able to do this from inside the program itself. You'll need another program to measure the timer, then launch your program, then measure the timer again once your program reaches the first line of main.

 

What language are you using?

Before main is run, static data will be initialized. In some programs this can include running a lot of code (especially if certain singleton patterns are used).

 

There's no standard facility in C++ to specify the order that these static constructors will be executed... but there are per-platform hacks, e.g. on MSVC you can use init_seg to prioritize construction order for certain objects. You could use this to read from the timer, which will give you a value after the CRT is initialized, but before any of your other code has run.

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What language are you using?

Before main is run, static data will be initialized. In some programs this can include running a lot of code (especially if certain singleton patterns are used).

 

There's no standard facility in C++ to specify the order that these static constructors will be executed... but there are per-platform hacks, e.g. on MSVC you can use init_seg to prioritize construction order for certain objects. You could use this to read from the timer, which will give you a value after the CRT is initialized, but before any of your other code has run.

 

I am using c only; (though i can compile such c code (not any c++ feature used in it) in c++ mode (c do not alow using const as an array size so i switch to c++, but this is just c code)

 

I do not think then that i have such initialization goes before my main where i eventualy put them - but do not know if some linked  libs can do that  - can they do fire it  before may main just by fact of static  linking it?

 

But besides it there is loader - which loads images  and setups something (possibly setups a lot)

 

There is also crt-setup you mention as far as I know (doin something with setupping fpu or something)

 

If somebody could say what can go in more detail on this startup  (under windows/winapi c program) I  would appreciate such thread

Edited by fir

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