Hello, Just for curiosity I was playing with SLURM fanout tree and found myself confused by set_span results. Let's assume that we have TreeWidth set to 3. Here is some spawn values and real assignment numbers for different spawn node count:
node count=10, span: 3 3 3 ; assign: 4 4 1. node count=11, span: 4 3 3 ; assign: 5 4 1. node count=12, span: 5 3 3 ; assign: 6 4 1. node count=13, span: 6 3 3 ; assign: 7 4 1. node count=14, span: 6 4 3 ; assign: 7 5 1. node count=15, span: 6 5 3 ; assign: 7 6 1. node count=16, span: 6 6 3 ; assign: 7 7 1. node count=17, span: 6 6 4 ; assign: 7 7 2. node count=18, span: 6 6 5 ; assign: 7 7 3. node count=19, span: 6 6 6 ; assign: 7 7 4. node count=20, span: 7 6 6 ; assign: 8 7 4. So looking for 10 nodes span you can assume that you intend to launch on 3 nodes each of which will subsequently launch 3 childrens. But actual assignment (see assign field) will be: first 2 nodes launch 3 childrens and last one will launch only one. The confusion comes from the fact that we give total node count (including direct childs) to set_spawn. And at the time of forwarding direct childrens are not counted in span. I tried to address this issue (check attached file) and have following results: new: count=10, span: 3 3 0 ; assign: 4 4 1. count=11, span: 3 3 1 ; assign: 4 4 2. count=12, span: 3 3 2 ; assign: 4 4 3. count=13, span: 3 3 3 ; assign: 4 4 4. count=14, span: 4 3 3 ; assign: 5 4 4. count=15, span: 5 3 3 ; assign: 6 4 4. count=16, span: 6 3 3 ; assign: 7 4 4. count=17, span: 6 4 3 ; assign: 7 5 4. count=18, span: 6 5 3 ; assign: 7 6 4. count=19, span: 6 6 3 ; assign: 7 7 4. count=20, span: 6 6 4 ; assign: 7 7 5. Here the span numbers correlate with assign numbers. So I am curious: is the current version of set_span correct and if so what is the rationale behind this. -- С Уважением, Поляков Артем Юрьевич Best regards, Artem Y. Polyakov
set_spawn_demo.tar.bz2
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