Messages in this thread | | | From | Valentin Schneider <> | Subject | [PATCH v3 0/7] sched: Instrument sched domain flags | Date | Wed, 1 Jul 2020 20:06:48 +0100 |
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Hi,
I've repeatedly stared at an SD flag and asked myself "how should that be set up in the domain hierarchy anyway?". I figured that if we formalize our flags zoology a bit, we could also do some runtime assertions on them - this is what this series is all about.
Patches =======
The idea is to associate the flags with metaflags that describes how they should be set in a sched domain hierarchy ("if this SD has it, all its {parents, children} have it") or how they behave wrt degeneration - details are in the comments and commit logs.
The good thing is that the debugging bits go away when CONFIG_SCHED_DEBUG isn't set. The bad thing is that this replaces SD_* flags definitions with some unsavoury macros. This is mainly because I wanted to avoid having to duplicate work between declaring the flags and declaring their metaflags.
o Patches 1-2 set up the SD flag definition groundwork o Patch 3 enables the hierarchy debugging o Patch 4 is a derelict SD flag removal o Patches 5-7 tweak the SD degeneration to leverage metaflags as well (suggested by Peter).
Note that this builds a compile-time mask using the single most horrendous macro I have ever presented to the public eye. It might end up being much better to explicitely build the mask in topology.h, but to be honest I felt like I had to show that monster around out of morbid fascination.
Revisions =========
v2 -> v3 --------
o Reworded comment for SD_OVERLAP (it's about the groups, not the domains)
o Added more flags to the SD degeneration mask o Added generation of an SD flag mask for the degeneration functions (Peter)
RFC -> v2 ---------
o Rebased on top of tip/sched/core o Aligned wording of comments between flags o Rectified some flag descriptions (Morten) o Added removal of SD_SHARE_POWERDOMAIN (Morten)
Valentin Schneider (7): sched/topology: Split out SD_* flags declaration to its own file sched/topology: Define and assign sched_domain flag metadata sched/topology: Verify SD_* flags setup when sched_debug is on arm, sched/topology: Remove SD_SHARE_POWERDOMAIN sched/topology: Add more flags to the SD degeneration mask sched/topology: Introduce SD metaflag for flags needing > 1 groups sched/topology: Use prebuilt SD flag degeneration mask
arch/arm/kernel/topology.c | 2 +- include/linux/sched/sd_flags.h | 153 +++++++++++++++++++++++++++++++++ include/linux/sched/topology.h | 36 +++++--- kernel/sched/topology.c | 40 +++++---- 4 files changed, 197 insertions(+), 34 deletions(-) create mode 100644 include/linux/sched/sd_flags.h
-- 2.27.0
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