16d4acbaca
The 'D' is now capital to clarify pronunciation. DBus service name is kept as '/Tuned' not to break backward compatibility. This will also need update of downstream tests which rely on the specific output strings containing the name. Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>
95 lines
2.5 KiB
Text
95 lines
2.5 KiB
Text
[id="variables-and-built-in-functions-in-tuned-profiles_{context}"]
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= Variables and built-in functions in TuneD profiles
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Variables and built-in functions expand at run time when a *TuneD* profile is activated.
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Using *TuneD* variables reduces the amount of necessary typing in *TuneD* profiles. You can also:
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* Use various built-in functions together with *TuneD* variables
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* Create custom functions in Python and add them to *TuneD* in the form of plug-ins
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[discrete]
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== Variables
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There are no predefined variables in *TuneD* profiles. You can define your own variables by creating the `[variables]` section in a profile and using the following syntax:
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[subs=+quotes]
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----
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[variables]
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[replaceable]__variable_name__=[replaceable]__value__
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----
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To expand the value of a variable in a profile, use the following syntax:
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[subs=+quotes]
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----
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${[replaceable]__variable_name__}
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----
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.Isolating CPU cores using variables
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====
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In the following example, the `${isolated_cores}` variable expands to `1,2`; hence the kernel boots with the [option]`isolcpus=1,2` option:
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----
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[variables]
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isolated_cores=1,2
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[bootloader]
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cmdline=isolcpus=${isolated_cores}
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----
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The variables can be specified in a separate file. For example, you can add the following lines to [filename]`tuned.conf`:
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[subs=+quotes]
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----
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[variables]
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include=/etc/tuned/[replaceable]_my-variables.conf_
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[bootloader]
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cmdline=isolcpus=${isolated_cores}
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----
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If you add the [option]`isolated_cores=1,2` option to the [filename]`/etc/tuned/my-variables.conf` file, the kernel boots with the [option]`isolcpus=1,2` option.
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====
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[discrete]
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== Functions
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To call a function, use the following syntax:
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[subs=+quotes]
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----
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${f:[replaceable]__function_name__:[replaceable]__argument_1__:[replaceable]__argument_2__}
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----
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To expand the directory path where the profile and the `tuned.conf` file are located, use the `PROFILE_DIR` function, which requires special syntax:
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----
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${i:PROFILE_DIR}
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----
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.Isolating CPU cores using variables and built-in functions
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====
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In the following example, the `${non_isolated_cores}` variable expands to `0,3-5`, and the `cpulist_invert` built-in function is called with the `0,3-5` argument:
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----
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[variables]
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non_isolated_cores=0,3-5
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[bootloader]
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cmdline=isolcpus=${f:cpulist_invert:${non_isolated_cores}}
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----
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The `cpulist_invert` function inverts the list of CPUs. For a 6-CPU machine, the inversion is `1,2`, and the kernel boots with the [option]`isolcpus=1,2` command-line option.
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====
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.Additional resources
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* The `tuned.conf(5)` man page
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