scx_layered: Make layered idle CPU selection topology aware #683
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Make idle CPU selection topology aware. Signed-off-by: Daniel Hodges <[email protected]>
Signed-off-by: Daniel Hodges <[email protected]>
Signed-off-by: Daniel Hodges <[email protected]>
htejun
approved these changes
Sep 24, 2024
| } | ||
| bpf_cpumask_copy(pref_idle_cpumask, idle_cpumask); | ||
| bpf_cpumask_and(pref_idle_cpumask, cache_cpumask, pref_idle_cpumask); | ||
| bpf_cpumask_and(pref_idle_cpumask, layer_cpumask, pref_idle_cpumask); |
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This is likely okay for now but cpumasks can become rather big and these cpumask manipulations can become expensive. Down the line, it probably would make sense to maintain these masks persistently in each layer.
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That makes sense and then we'd only have to update the masks when the layers change size.
| @@ -1030,7 +1076,7 @@ static bool keep_running(struct cpu_ctx *cctx, struct task_struct *p) | |||
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| /* | |||
| * If @p is in an open layer, keep running if there's any idle | |||
| * CPU. If confined, keep running iff the layer has idle CPUs. | |||
| * CPU. If confined, keep running if the layer has idle CPUs. | |||
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I think iff is intentional, meaning if and only if.
Fix comment to be more accurate. Signed-off-by: Daniel Hodges <[email protected]>
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Make scx_layered idle CPU selection topology aware. It first tries to select an idle CPU from the local LLC before attempting to select an idle CPU from the local node.