Re: Ada memory management seems slow

[Robert A Duff <bobduff@shell01.TheWorld.com>]

"Makhno" <root@127.0.0.1> writes:

> > GNAT uses malloc and free from the C library  for memory management - so
> > performace is the same as with C. Only with C nobody measures the
> > performance - people just expect malloc and free to be as fast as 
> > possible.
> 
> I find this difficult to believe - I have experience of using free() in C, 
> and unless the lists are far bigger than I think they are, C is nowhere near 
> as slow as this.
> Is there any way I can check precisely what Ada is using?

You can dump out the assembly language produced by the compiler.
You can read the run-time library sources.
You can single-step through the code using gdb.

>...The program is
> calling something called FREE which is defined as some sort of deallocator 
> called Ada.Unchecked_Deallocation

Yeah, that's the usual way to deallocate things in Ada --
Unchecked_Deallocation is pretty-much analogous to free() in C.

I'm pretty sure Unchecked_Deallocation uses the same "free()" that C
code would use.  It's not very efficient (I've written more
efficient allocators), but it's not horrible.

What makes you think that memory deallocation is the problem?
Perhaps some other code is causing the problem.
I mentioned finalization in another post.
Also, Ada needs to do some locking around memory [de]allocation
primitives; that might be something to look into.

- Bob