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sched_deadline, docs: replace rt-app examples with chrt or use config.json

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rt-app no longer accepts command-line arguments. So, replace rt-app example
with chrt and use the JSON format in the other example instead of command-
line arguments.

Signed-off-by: Shashank Balaji <shashank.mahadasyam@sony.com>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250527-sched-deadline-cpu-affinity-v2-1-b8b40a4feefa@sony.com
This commit is contained in:
Shashank Balaji
2025-05-27 23:55:57 +09:00
committed by Jonathan Corbet
parent c361f76da6
commit ab8531cdb1
1 changed files with 30 additions and 18 deletions
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48
Documentation/scheduler/sched-deadline.rst
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@@ -678,8 +678,7 @@ Deadline Task Scheduling
5.1 SCHED_DEADLINE and cpusets HOWTO
------------------------------------
An example of a simple configuration (pin a -deadline task to CPU0)
follows (rt-app is used to create a -deadline task)::
An example of a simple configuration (pin a -deadline task to CPU0) follows::
mkdir /dev/cpuset
mount -t cgroup -o cpuset cpuset /dev/cpuset
@@ -692,8 +691,7 @@ Deadline Task Scheduling
echo 1 > cpu0/cpuset.cpu_exclusive
echo 1 > cpu0/cpuset.mem_exclusive
echo $$ > cpu0/tasks
rt-app -t 100000:10000:d:0 -D5 # it is now actually superfluous to specify
# task affinity
chrt --sched-runtime 100000 --sched-period 200000 --deadline 0 yes > /dev/null
6. Future plans
===============
@@ -731,24 +729,38 @@ Appendix A. Test suite
behaves under such workloads. In this way, results are easily reproducible.
rt-app is available at: https://github.com/scheduler-tools/rt-app.
Thread parameters can be specified from the command line, with something like
this::
rt-app does not accept command line arguments, and instead reads from a JSON
configuration file. Here is an example ``config.json``:
# rt-app -t 100000:10000:d -t 150000:20000:f:10 -D5
.. code-block:: json
The above creates 2 threads. The first one, scheduled by SCHED_DEADLINE,
executes for 10ms every 100ms. The second one, scheduled at SCHED_FIFO
priority 10, executes for 20ms every 150ms. The test will run for a total
of 5 seconds.
{
"tasks": {
"dl_task": {
"policy": "SCHED_DEADLINE",
"priority": 0,
"dl-runtime": 10000,
"dl-period": 100000,
"dl-deadline": 100000
},
"fifo_task": {
"policy": "SCHED_FIFO",
"priority": 10,
"runtime": 20000,
"sleep": 130000
}
},
"global": {
"duration": 5
}
}
More interestingly, configurations can be described with a json file that
can be passed as input to rt-app with something like this::
On running ``rt-app config.json``, it creates 2 threads. The first one,
scheduled by SCHED_DEADLINE, executes for 10ms every 100ms. The second one,
scheduled at SCHED_FIFO priority 10, executes for 20ms every 150ms. The test
will run for a total of 5 seconds.
# rt-app my_config.json
The parameters that can be specified with the second method are a superset
of the command line options. Please refer to rt-app documentation for more
details (`<rt-app-sources>/doc/*.json`).
Please refer to the rt-app documentation for the JSON schema and more examples.
The second testing application is done using chrt which has support
for SCHED_DEADLINE.