diff options
| author | Michal Koutný <mkoutny@suse.com> | 2024-12-11 18:00:52 +0100 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2024-12-13 08:40:43 -0700 |
| commit | bbf5254a5ab18b5a17e0c11a91a42d50a92bb5e1 (patch) | |
| tree | f9bdad0fa9574b412a7a9c575746350691ad49d4 | |
| parent | 80568f479b65a2d3e85125a20a51af09e1cc7ea8 (diff) | |
Documentation: sched/RT: Update paragraphs about RT bandwidth control
This has slightly changed with the introduction of fair_server.
Update the most relevant parts.
Link: https://lore.kernel.org/r/Z0c8S8i3qt7SEU14@jlelli-thinkpadt14gen4.remote.csb/
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241211170052.2449581-1-mkoutny@suse.com
| -rw-r--r-- | Documentation/scheduler/sched-deadline.rst | 13 | ||||
| -rw-r--r-- | Documentation/scheduler/sched-rt-group.rst | 8 |
2 files changed, 11 insertions, 10 deletions
diff --git a/Documentation/scheduler/sched-deadline.rst b/Documentation/scheduler/sched-deadline.rst index 22838ed8e13a..a727827b8dd5 100644 --- a/Documentation/scheduler/sched-deadline.rst +++ b/Documentation/scheduler/sched-deadline.rst @@ -591,12 +591,13 @@ Deadline Task Scheduling The system wide settings are configured under the /proc virtual file system. - For now the -rt knobs are used for -deadline admission control and the - -deadline runtime is accounted against the -rt runtime. We realize that this - isn't entirely desirable; however, it is better to have a small interface for - now, and be able to change it easily later. The ideal situation (see 5.) is to - run -rt tasks from a -deadline server; in which case the -rt bandwidth is a - direct subset of dl_bw. + For now the -rt knobs are used for -deadline admission control and with + CONFIG_RT_GROUP_SCHED the -deadline runtime is accounted against the (root) + -rt runtime. With !CONFIG_RT_GROUP_SCHED the knob only serves for the -dl + admission control. We realize that this isn't entirely desirable; however, it + is better to have a small interface for now, and be able to change it easily + later. The ideal situation (see 5.) is to run -rt tasks from a -deadline + server; in which case the -rt bandwidth is a direct subset of dl_bw. This means that, for a root_domain comprising M CPUs, -deadline tasks can be created while the sum of their bandwidths stays below: diff --git a/Documentation/scheduler/sched-rt-group.rst b/Documentation/scheduler/sched-rt-group.rst index d685609ed3d7..80b05a3009ea 100644 --- a/Documentation/scheduler/sched-rt-group.rst +++ b/Documentation/scheduler/sched-rt-group.rst @@ -92,10 +92,10 @@ The system wide settings are configured under the /proc virtual file system: /proc/sys/kernel/sched_rt_runtime_us: A global limit on how much time real-time scheduling may use. This is always less or equal to the period_us, as it denotes the time allocated from the - period_us for the real-time tasks. Even without CONFIG_RT_GROUP_SCHED enabled, - this will limit time reserved to real-time processes. With - CONFIG_RT_GROUP_SCHED=y it signifies the total bandwidth available to all - real-time groups. + period_us for the real-time tasks. Without CONFIG_RT_GROUP_SCHED enabled, + this only serves for admission control of deadline tasks. With + CONFIG_RT_GROUP_SCHED=y it also signifies the total bandwidth available to + all real-time groups. * Time is specified in us because the interface is s32. This gives an operating range from 1us to about 35 minutes. |