[Beowulf] Again about NUMA (numactl and taskset)

Mark Hahn hahn at mcmaster.ca
Mon Jun 23 12:12:48 PDT 2008

> "how sure are we that a process (or thread) that allocated and initialized 
> and writes to memory at a single specific memory node,
> also keeps getting scheduled at a core on that memory node?"

numactl --cpubind=0 --membind=0

> It seems to me that sometimes (like every second or so) threads jump from 1 
> memory node to another. I could be wrong,
> but i certainly have that impression with the linux kernels.

you can always tie a thread to a core.  for non-bound threads,
the question is really how long the kernel should leave a runnable thread 
"on" a busy cpu before running it on another (idle) cpu.  the kernel
does try to avoid this, but how hard has in the past depended on the 
kernel's guess about the cache footprint of the thread and its "natural"
timeslice (how long it typically runs before yielding.)

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