On Tue, 2003-10-21 at 14:27, Christopher Browne wrote: > In the last exciting episode, [EMAIL PROTECTED] (Josh Berkus) wrote: > > So what is the ceiling on 32-bit processors for RAM? Most of the > > 64-bit vendors are pushing Athalon64 and G5 as "breaking the 4GB > > barrier", and even I can do the math on 2^32. All these 64-bit > > vendors, then, are talking about the limit on ram *per application* > > and not per machine? > > I have been seeing ia-32 servers with 8GB of RAM; it looks as though > there are ways of having them support ("physically, in theory, if you > could get a suitable motherboard") as much as 64GB. > > But that certainly doesn't get you past 2^32 bytes per process, and > possibly not past 2^31 bytes/process. > > >From Linux kernel help: > > CONFIG_NOHIGHMEM: > > Linux can use up to 64 Gigabytes of physical memory on x86 > systems. However, the address space of 32-bit x86 processors is > only 4 Gigabytes large. That means that, if you have a large > amount of physical memory, not all of it can be "permanently > mapped" by the kernel. The physical memory that's not permanently > mapped is called "high memory". > > And that leaves open the question of how much shared memory you can > address. That presumably has to fit into the 4GB, and if your > PostgreSQL processes had (by some fluke) 4GB of shared memory, there > wouldn't be any "local" memory for sort memory and the likes. > > Add to that the consideration that there are reports of Linux "falling > over" when you get to right around 2GB/4GB. I ran a torture test a > while back that _looked_ like it was running into that; I can't verify > that, unfortunately.
Well thank goodness that Linux & Postgres work so well on Alpha and long-mode AMD64. -- ----------------------------------------------------------------- Ron Johnson, Jr. [EMAIL PROTECTED] Jefferson, LA USA "Fear the Penguin!!" ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings