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