On 30 Jun 2008, at 15:00, Richard Frith-Macdonald wrote:
On 30 Jun 2008, at 12:33, David Chisnall wrote:
My man page for vmalloc states:
The obsolete function valloc() allocates size bytes and
returns a pointer to the allocated memory. The memory address
will be a
multiple of the page
size. It is equivalent to memalign(sysconf(_SC_PAGESIZE),size).
I'm not sure whether you are aware of the fact that this function
is
considered obsolete.
Not according to POSIX, however it is recommended that applications
use mmap or malloc if possible. In our case, the ideal solution
would be a dedicated, mmap-backed, NSZone for allocating invocation
trampolines.
Sounds good.
At the moment I'm just concentrating on getting libffi working
reliably, but I'd love to add better performing code if you can
provide it.
The idea of per-thread allocation sounds good, but even better if it
cold somehow be integrated with the autorelease mechanism so that we
can minimise the number of times we look up the current thread,
while ensuring that we never leak memory.
On every platform platfrom that uses ELF, and on Windows, we can use
thread-local static storage (__thread in the declaration). This is
very cheap (just an indirect lookup via the thread register) and as
long as we remember to deallocate the NSZone in NSThread's destructor
we won't leak.
Another option might be to extend NSAutoreleasePool to integrate an
allocator. This is actually a very nice idea, since it gives us a
simple means of building generational garbage collection (each object
could allocate itself by sending a message to the NSAutoreleasePool on
the top of the stack, which could then promote objects into the longer
running generation (parent pool on the stack) or delete them when it
was destroyed. This is a much bigger project though, and not one I'll
be able to look at for a few months (although I'd like to eventually,
since it seems a better solution to add allocation to
NSAutoreleasePool and loop detection to NSObject than the horrible
hacks that Apple have used to wedge GC into Objective-C 2.0).
David
_______________________________________________
Gnustep-dev mailing list
[email protected]
http://lists.gnu.org/mailman/listinfo/gnustep-dev
