On Tue, Apr 05, 2011 at 02:11:02AM -0400, STeve Andre' wrote:
> On 04/05/11 01:31, Otto Moerbeek wrote:
> >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
>
> All right, let me ask again, or a little differently. I understand
> what you are saying, but the 32 bit limit on amd64 has surprised
> a lot of people lately (I know, they didn't read up).
>
> How much physical memory can I stuff into an amd64 box now?
>
> Could I have a 64G machine and run ten 6G processes without
> swapping?
>
> --STeve Andre'
I don't know enough to answer this. There might be other limitations
kicking in.
But currently you at least have a chance.
-Otto
