[PATCH] Documentation: scheduler: fix outdated information on arch SD flags and sched_domain

[Barry Song]

This document seems to be out of date for many, many years. Even it has
misspelled from the first day.
ARCH_HASH_SCHED_TUNE should be ARCH_HAS_SCHED_TUNE
ARCH_HASH_SCHED_DOMAIN should be ARCH_HAS_SCHED_DOMAIN

But since v2.6.14, kernel completely deleted the relevant code and even
arch_init_sched_domains() was deleted.

Right now, kernel is asking architectures to call set_sched_topology() to
override the default sched domains.

Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Adrian Freund <adrian@xxxxxxxxx>
Signed-off-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx>
---
 Documentation/scheduler/sched-domains.rst | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/Documentation/scheduler/sched-domains.rst b/Documentation/scheduler/sched-domains.rst
index 5c4b7f4f0062..434d4e7e86c5 100644
--- a/Documentation/scheduler/sched-domains.rst
+++ b/Documentation/scheduler/sched-domains.rst
@@ -69,15 +69,9 @@ The implementor should read comments in include/linux/sched.h:
 struct sched_domain fields, SD_FLAG_*, SD_*_INIT to get an idea of
 the specifics and what to tune.
 
-Architectures may retain the regular override the default SD_*_INIT flags
-while using the generic domain builder in kernel/sched/core.c if they wish to
-retain the traditional SMT->SMP->NUMA topology (or some subset of that). This
-can be done by #define'ing ARCH_HASH_SCHED_TUNE.
-
-Alternatively, the architecture may completely override the generic domain
-builder by #define'ing ARCH_HASH_SCHED_DOMAIN, and exporting your
-arch_init_sched_domains function. This function will attach domains to all
-CPUs using cpu_attach_domain.
+Architectures may override the generic domain builder and the default
+SD_*_INIT flags by define'ing an array of sched_domain_topology_level and
+calling set_sched_topology() with this array as the parameter.
 
 The sched-domains debugging infrastructure can be enabled by enabling
 CONFIG_SCHED_DEBUG. This enables an error checking parse of the sched domains
-- 
2.25.1