Interleaved allocation

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Hello,

I'm trying to understand what's the exact behavior of the
interleaved allocation in libnuma. I have two questions, the first
regarding numa_alloc_interleaved() and the second regarding numactl.
Suppose I'm running in a 4-node machine.

1. What happens when I try to allocate 100 pages with a call like this:

numa_alloc_interleaved(100 * numa_pagesize())

I can think of two possible allocation schemes:
a. Pages 0-24 are allocated to node 0, pages 25-49 are allocated to
node 1, pages 50-74 are allocated on node 2 and pages 75-99 are
allocated on node 3.

b. Pages 0,4,8... are allocated on node 0, pages 1,5,9... are
allocated on node 1 and so on

2. What's the effect of using numactl --interleaved=0,1,2,3 -- ./myprog?
I would assume it "substitutes" any malloc's to
numa_alloc_interleaved(), but I'm not sure if it's just that.

Thank you,
Martin

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