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 a metatype that describes how they
should be set in a sched domain hierarchy - details are in the comments and
commit logs. For now it's just a simple parent/children relationship
description ("if this SD has it, all its {parents, children} have it").
The good thing is that this all goes away when CONFIG_SCHED_DEBUG isn't
set. The bad thing is that 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 metatypes.
There's also the removal of yet another SD flag (SD_SHARE_POWERDOMAIN).
Some deltas
===========
This time around it's a slight size increase (w/o SCHED_DEBUG):
$ compare.sh before after vmlinux.o
cpu_attach_domain 996 1000 +4
build_sched_domains 4716 4728 +12
Comparing the objdumps side by side, nothing obvious stands out to me.
Revisions
=========
RFC -> v2
---------
RFC at:
https://lkml.kernel.org/r/[email protected]
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)
Cheers,
Valentin
Valentin Schneider (4):
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
arch/arm/kernel/topology.c | 2 +-
include/linux/sched/sd_flags.h | 133 +++++++++++++++++++++++++++++++++
include/linux/sched/topology.h | 29 +++----
kernel/sched/topology.c | 27 +++++--
4 files changed, 169 insertions(+), 22 deletions(-)
create mode 100644 include/linux/sched/sd_flags.h
--
2.27.0
