Hi Joel/Jos, It is a per process access. If I can summarise like this: a. 3GB per process memory access is still the limit for RH9, FC1 and RHES 3. b. The 2.4 kernels can support up to 64GB memory. c. RH9 and presumably RHES 3 as well automatically produce bigmem kernel to support memory size over 4GB. d. FC1 will require a manual step to tune up the kernel to support memory size > 4GB. e. 4GB memory or more may incure 4-6% additional performance overhead. f. 2.6 kernels support up to 512GB memory, and g. Opterons in theory can support up to 1TB of virtual memory. Peter -----Original Message----- From: Joel Jaeggli [mailto:joelja@xxxxxxxxxxxxxxxxxxxx] Sent: 27 January 2004 19:57 To: 'fedora-list@xxxxxxxxxx' Cc: Chiu, PCM (Peter) Subject: RE: maximum memory capacity On Tue, 27 Jan 2004, Chiu, PCM (Peter) wrote: > Thanks, Joel, > > My experience on a dual Xeon 2.4GHz cpus, 6GB memory with RH 9 and > bigmem kernel allows us to access physical memory size up to 3GB but > not beyond. on a per process basis or overall? it should be work given what's documented, individual processes will never exceed 3GB though... > Do you know if it is possible to do so under FC1, or RHES, or none of > them? fc1 has no bigmem kernels... you you get to rebuilt the normal one with 64GB supported turned on... RHES you get support for that from the vendor... ymmv > Peter > > -----Original Message----- > From: fedora-list-admin@xxxxxxxxxx > [mailto:fedora-list-admin@xxxxxxxxxx] On Behalf Of Joel Jaeggli > Sent: 26 January 2004 17:27 > To: 'fedora-list@xxxxxxxxxx' > Subject: RE: maximum memory capacity > > > On Mon, 26 Jan 2004, Chiu, PCM (Peter) wrote: > > > Thanks, my understanding on 32-bit based platforms, the limitation > > is > > 4GB. > > linux on x86 can support up to 64GB of ram... address space is 4GB so > not all of it gets permently mapped... kernels aren't generally > compiled for 64GB because the address extensions will prevent the > kernel from booting on cpu's that don't support it... that said you'll > have a fair performance tradeoff to consider with more than 4GB of ram > (3%-6% more overhead depending on the application). also the most > memory an individual process can use is 3GB of ram. > > > Opterons or Itanium can lift this limitation. > > The opteron's long mode supports 1TB of addressable memory the current > 2.6.X support 512GB as I understand it... populating an opteron mainboard > with more than 16-20GB of ram (tyan s4880 has 10 dimm sockets) is left as > an exerercise for the reader. > > > But not sure what their latest status. > > > > Peter > > -----Original Message----- > > From: fedora-list-admin@xxxxxxxxxx > > [mailto:fedora-list-admin@xxxxxxxxxx] On Behalf Of WipeOut > > Sent: 26 January 2004 15:02 > > To: fedora-list@xxxxxxxxxx > > Subject: Re: maximum memory capacity > > > > > > Chiu, PCM (Peter) wrote: > > > > >Can anyone tell me the maximum physical and virtual memory sizes > > >supported under FC1? > > > > > >I am trying to work out the technical differences between RHES and > > >FC1 > > >to enable us to choose the appropriate version to use. I am aware of > > >the initial licenses and maintenance issues. > > > > > >Many Thanks. > > > > > >Peter > > > > > > > > > > > > > > Something says to me that the standard Fedora kernel is setup for > > 4GB > > (I > > amy be wrong).. But there is nothing stopping you building a kernel for > > larger amounts of memory.. > > > > later.. > > > > > > > > -- -------------------------------------------------------------------------- Joel Jaeggli Unix Consulting joelja@xxxxxxxxxxxxxxxxxxxx GPG Key Fingerprint: 5C6E 0104 BAF0 40B0 5BD3 C38B F000 35AB B67F 56B2
