Re: Large arrays (again), problem case for GNAT

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 14 Apr 2005 11:18:22 -0400, Robert A Duff wrote:

> The reason I like allocate-on-write is that it is very useful to
> allocate a huge array, and then only use some part of it.  That way, the
> program can deal with enormous input data, without paying the cost when
> the input data is small.  Physical memory is 1000 times more expensive
> than address space.

I think this approach is flawed. The contract of malloc is to return memory
not the address space. That must be just another system call.

Consider an application that needs contiguous address space. User storage
pool is an excellent example. The application must request the space from
OS telling something like: "reserve me 100GB and allocate n bytes starting
from the first address." After that it could allocate memory *within* that
space by pieces as needed. For this it would simply use realloc instead of
malloc. No need to break contracts.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de