Messages in this thread | | | Date | Fri, 4 Dec 2020 14:31:15 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH 06/10] sched/fair: Clear the target CPU from the cpumask of CPUs searched |
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On Fri, Dec 04, 2020 at 02:47:48PM +0100, Vincent Guittot wrote: > > IIUC, select_idle_core and select_idle_cpu share the same cpumask(select_idle_mask)? > > If the target's sibling is removed from select_idle_mask from select_idle_core(), > > select_idle_cpu() will lose the chance to pick it up? > > This is only relevant for patch 10 which is not to be included IIUC > what mel said in cover letter : "Patches 9 and 10 are stupid in the > context of this series." >
Patch 10 was stupid in the context of the prototype because select_idle_core always returned a CPU. A variation ended up being reintroduced at the end of the Series Yet To Be Posted so that SMT siblings are cleared during select_idle_core() but select_idle_cpu() still has a mask with unvisited CPUs to consider if no idle cores are found.
As far as I know, this would still be compatible with Aubrey's idle cpu mask as long as it's visited and cleared between select_idle_core and select_idle_cpu. It relaxes the contraints on Aubrey to some extent because the idle cpu mask would be a hint so if the information is out of date, an idle cpu may still be found the normal way.
-- Mel Gorman SUSE Labs
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