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| author |   Barry Song <song.bao.hua@hisilicon.com> | 2020-11-14 00:50:18 +1300 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2020-11-19 11:25:46 +0100 |
| commit | 9032dc211523f7cd5395302a0658c306249553f4 (patch) | |
| tree | 67fcfa9213db40200681312af243736c6e65dc80 /Documentation/scheduler | |
| parent | sched/topology: Warn when NUMA diameter > 2 (diff) | |
| download | wireguard-linux-9032dc211523f7cd5395302a0658c306249553f4.tar.xz wireguard-linux-9032dc211523f7cd5395302a0658c306249553f4.zip | |
Documentation: scheduler: fix information on arch SD flags, sched_domain and sched_debug
This document seems to be out of date for many, many years.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
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.
On the other hand, to print the schedule debug information, users need to
set sched_debug cmdline or enable it by sysfs entry. So this patch also
adds the description for sched_debug.
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20201113115018.1628-1-song.bao.hua@hisilicon.com
Diffstat (limited to 'Documentation/scheduler')
| -rw-r--r-- | Documentation/scheduler/sched-domains.rst | 26 |
1 files changed, 11 insertions, 15 deletions
diff --git a/Documentation/scheduler/sched-domains.rst b/Documentation/scheduler/sched-domains.rst index 5c4b7f4f0062..8582fa5e9170 100644 --- a/Documentation/scheduler/sched-domains.rst +++ b/Documentation/scheduler/sched-domains.rst @@ -65,21 +65,17 @@ of the SMP domain will span the entire machine, with each group having the cpumask of a node. Or, you could do multi-level NUMA or Opteron, for example, might have just one domain covering its one NUMA level. -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. +The implementor should read comments in include/linux/sched/sd_flags.h: +SD_* to get an idea of the specifics and what to tune for the SD flags +of a sched_domain. -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 flags +for a given topology level by creating a sched_domain_topology_level array 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 -which should catch most possible errors (described above). It also prints out -the domain structure in a visual format. +CONFIG_SCHED_DEBUG and adding 'sched_debug' to your cmdline. If you forgot to +tweak your cmdline, you can also flip the /sys/kernel/debug/sched_debug +knob. This enables an error checking parse of the sched domains which should +catch most possible errors (described above). It also prints out the domain +structure in a visual format. |