Am Freitag, 14. Dezember 2012, 01:44:26 schrieb Grant: > > > So if I have 2 physical CPU's with 4 cores each and I enable SMP, I'm > > using > > > > 8 cores? Can NUMA be either enabled or disabled when using more than > > one > > > > physical CPU, or is it required? > > > > NUMA is a hardware architecture. It's how you access memory on a > > hardware level: NUMA = Non Uniform Memory Access vs a UMA architecture > > of typical (old/legacy) SMP systems (UMA = Uniform Memory Access). > > > > In a UMA system, all the memory belongs to all the sockets. In a NUMA > > system, each socket has it's "own" local memory. In modern (x86-64) > > processors, each socket has it's own memory controller so each socket > > controls its own local memory. If one socket runs out of memory it can > > ask another socket to lend him some memory. In a UMA system, no socket > > has to ask since memory is global and belongs to all sockets so if one > > socket uses up all the memory ... the rest "starve". In NUMA, there's > > more control over who uses what (be it cores or RAM). > > > > If you have a modern dual or quad (or higher #) socket system ... > > you've got NUMA architecture and you can't get rid of it, it's > > hardware, not software. > > So I must enable CONFIG_NUMA for more than one physical CPU, and disable it > for only one physical CPU?
you never need numa for one cpu. Ok? And even if you have several, you will probably never need it. -- #163933
