On Tue, Apr 05, 2011 at 12:57:28AM -0400, STeve Andre' wrote:
> On 04/05/11 00:52, Otto Moerbeek wrote:
> >On Mon, Apr 04, 2011 at 09:23:48PM -0400, STeve Andre' wrote:
> >
> >>On 04/04/11 19:59, Miod Vallat wrote:
> >>>>So, now that BIGMEM is up, what is the new max? are we talking TB?
> >>>>or is 8GB the new upper limit?
> >>>The limit of the number of vague questions for which there is only vague
> >>>answers is infinite.
> >>>
> >>>Which limit are you talking about? The limit of the number of open files
> >>>in the kernel? The limit of the number of distinct PCI busses in the
> >>>kernel? The limit of the number of distinct keys handled at the keyboard
> >>>driver level? The limit of profanity comments in the kernel source code?
> >>>
> >>>Miod
> >>I think the (first) question is how much memory can be addressed?
> >>
> >>--STeve Andre'
> >As vague as the first question. Addressing memory is done from a context.
> >
> > -Otto
> Hmm. OK -- can amd64 then handle 256G of memory?
Still missing context. There's the kernel and userland, physical and
virtual memory to name a few things that tell a bit about context.
MAXDSIZE is the maximum of virtual memory a process can allocate using
malloc and similar mechanisms.
MAXDSIZE has already been at 8GB for a while. That didn't change with
bigmem, which talks about addressable physical memory from the kernel.
The two limits have no immediate connection. So the answer is: no,
enabling bigmem did not change MAXDSIZE. Processes cannot allocate
more virtual memory from the heap with bigmem enabled.
Of course now that the kernel can address more physical memory, it
might consider backing more of the allocated virtual memory with
physical pages at any point in time.
-Otto
