GC_enable_incremental()

Thu Sep 9 00:42:00 GMT 2004

We could. The collector used to encourage that, but it turns out
it's actually a bit tricky if system calls block for multiple
GCs, etc. 
I think it's not terribly hard to ensure that
1) We don't really turn on incremental GC unless the page size is
such that pointer-free objects do not have to be protected.
2) System calls only write to objects that the collector knows
are pointer-free, or that are not in the collected heap.
I think we do at least 95% of (2). And it's probably easy to
do the other 5%. It's just that nobody has ever checked carefully.
Hans
> -----Original Message-----
> From: Andrew Haley [mailto:aph@redhat.com]
> Sent: Wednesday, September 08, 2004 8:48 AM
> To: Hans Boehm
> Cc: Bryce McKinlay; 'DHollenbeck'; java@gcc.gnu.org
> Subject: Re: GC_enable_incremental()
>>> Hans Boehm writes:
> > 
> > The problem isn't really a system call writing pointers. The
> > problem is that if a system call writes into the heap, the GC needs
> > to have been told in advance that that section of memory is
> > pointerfree. Otherwise the system call may fail, since the memory
> > may not be writable.
>> Interesting. Could we not intercept system calls?
>> Andrew.
>