Re: [PATCH v4 07/10] sched/topology: Add more flags to the SD degeneration mask

From: Ingo Molnar
Date: Thu Aug 06 2020 - 11:39:56 EST

* Valentin Schneider <valentin.schneider@xxxxxxx> wrote:

> I don't think it is going to change much in practice, but we were missing
> those:
> o SD_BALANCE_WAKE: Used just like the other SD_BALANCE_* flags, so also
> needs > 1 group.
> o SD_ASYM_PACKING: Hinges on load balancing (periodic / wakeup), thus needs
> > 1 group to happen
> o SD_OVERLAP: Describes domains with overlapping groups; can't have
> overlaps with a single group.
> SD_PREFER_SIBLING is as always the odd one out: we currently consider it
> in sd_parent_degenerate() but not in sd_degenerate(). It too hinges on load
> balancing, and thus won't have any effect when set on a domain with a
> single group. Add it to the sd_degenerate() groups mask.

Would be nice to add these one by one, just in case there's a
performance or boot regression with any of them.