linux-toradex.git/drivers/cpuidle/Kconfig, branch master

cpuidle: clean up dead dependencies on CPU_IDLE in Kconfig

2026-04-01T14:01:27+00:00

The Kconfig in the parent directory already has the first 'if CPU_IDLE'
gating the inclusion of this Kconfig, meaning that the 'depends on
CPUIDLE' statements in these config options are effectively dead code.

Leave the 'if CPU_IDLE...endif' condition, and remove the individual
'depends on' statements in Kconfig.mips and Kconfig.powerpc

This dead code was found by kconfirm, a static analysis tool for
Kconfig.

Signed-off-by: Julian Braha 
[ rjw: Subject and changelog edits ]
Link: https://patch.msgid.link/20260331074920.41269-1-julianbraha@gmail.com
Signed-off-by: Rafael J. Wysocki

cpuidle-haltpoll: select haltpoll governor

2023-01-13T19:50:46+00:00

The haltpoll cpuidle driver should select the haltpoll governor, so
as to ensure that they work together.

Signed-off-by: Li RongQing 
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki

cpuidle: Add RISC-V SBI CPU idle driver

2022-03-10T17:29:51+00:00

The RISC-V SBI HSM extension provides HSM suspend call which can
be used by Linux RISC-V to enter platform specific low-power state.

This patch adds a CPU idle driver based on RISC-V SBI calls which
will populate idle states from device tree and use SBI calls to
entry these idle states.

Signed-off-by: Anup Patel 
Signed-off-by: Anup Patel 
Acked-by: Atish Patra 
Signed-off-by: Palmer Dabbelt

cpuidle: Factor-out power domain related code from PSCI domain driver

2022-03-10T17:29:44+00:00

The generic power domain related code in PSCI domain driver is largely
independent of PSCI and can be shared with RISC-V SBI domain driver
hence we factor-out this code into dt_idle_genpd.c and dt_idle_genpd.h.

Signed-off-by: Anup Patel 
Signed-off-by: Anup Patel 
Reviewed-by: Ulf Hansson 
Signed-off-by: Palmer Dabbelt

cpuidle: Fix Kconfig indentation

2019-11-29T10:47:35+00:00

Adjust indentation from spaces to tab (+optional two spaces) as in
coding style with command like:
	$ sed -e 's/^        /\t/' -i */Kconfig

Signed-off-by: Krzysztof Kozlowski 
Signed-off-by: Rafael J. Wysocki

cpuidle: add haltpoll governor

2019-07-30T15:27:37+00:00

The cpuidle_haltpoll governor, in conjunction with the haltpoll cpuidle
driver, allows guest vcpus to poll for a specified amount of time before
halting.
This provides the following benefits to host side polling:

        1) The POLL flag is set while polling is performed, which allows
           a remote vCPU to avoid sending an IPI (and the associated
           cost of handling the IPI) when performing a wakeup.

        2) The VM-exit cost can be avoided.

The downside of guest side polling is that polling is performed
even with other runnable tasks in the host.

Results comparing halt_poll_ns and server/client application
where a small packet is ping-ponged:

host                                        --> 31.33
halt_poll_ns=300000 / no guest busy spin    --> 33.40   (93.8%)
halt_poll_ns=0 / guest_halt_poll_ns=300000  --> 32.73   (95.7%)

For the SAP HANA benchmarks (where idle_spin is a parameter
of the previous version of the patch, results should be the
same):

hpns == halt_poll_ns

                          idle_spin=0/   idle_spin=800/    idle_spin=0/
                          hpns=200000    hpns=0            hpns=800000
DeleteC06T03 (100 thread) 1.76           1.71 (-3%)        1.78   (+1%)
InsertC16T02 (100 thread) 2.14           2.07 (-3%)        2.18   (+1.8%)
DeleteC00T01 (1 thread)   1.34           1.28 (-4.5%)      1.29   (-3.7%)
UpdateC00T03 (1 thread)   4.72           4.18 (-12%)       4.53   (-5%)

Signed-off-by: Marcelo Tosatti 
Signed-off-by: Rafael J. Wysocki

add cpuidle-haltpoll driver

2019-07-30T15:27:37+00:00

Add a cpuidle driver that calls the architecture default_idle routine.

To be used in conjunction with the haltpoll governor.

Signed-off-by: Marcelo Tosatti 
Signed-off-by: Rafael J. Wysocki

treewide: Add SPDX license identifier - Makefile/Kconfig

2019-05-21T08:50:46+00:00

Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

cpuidle: New timer events oriented governor for tickless systems

2019-01-16T22:07:30+00:00

The venerable menu governor does some things that are quite
questionable in my view.

First, it includes timer wakeups in the pattern detection data and
mixes them up with wakeups from other sources which in some cases
causes it to expect what essentially would be a timer wakeup in a
time frame in which no timer wakeups are possible (because it knows
the time until the next timer event and that is later than the
expected wakeup time).

Second, it uses the extra exit latency limit based on the predicted
idle duration and depending on the number of tasks waiting on I/O,
even though those tasks may run on a different CPU when they are
woken up.  Moreover, the time ranges used by it for the sleep length
correction factors depend on whether or not there are tasks waiting
on I/O, which again doesn't imply anything in particular, and they
are not correlated to the list of available idle states in any way
whatever.

Also, the pattern detection code in menu may end up considering
values that are too large to matter at all, in which cases running
it is a waste of time.

A major rework of the menu governor would be required to address
these issues and the performance of at least some workloads (tuned
specifically to the current behavior of the menu governor) is likely
to suffer from that.  It is thus better to introduce an entirely new
governor without them and let everybody use the governor that works
better with their actual workloads.

The new governor introduced here, the timer events oriented (TEO)
governor, uses the same basic strategy as menu: it always tries to
find the deepest idle state that can be used in the given conditions.
However, it applies a different approach to that problem.

First, it doesn't use "correction factors" for the time till the
closest timer, but instead it tries to correlate the measured idle
duration values with the available idle states and use that
information to pick up the idle state that is most likely to "match"
the upcoming CPU idle interval.

Second, it doesn't take the number of "I/O waiters" into account at
all and the pattern detection code in it avoids taking timer wakeups
into account.  It also only uses idle duration values less than the
current time till the closest timer (with the tick excluded) for that
purpose.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Daniel Lezcano

cpuidle: Don't enable all governors by default

2016-01-15T21:39:58+00:00

Since commit d6f346f2d2 (cpuidle: improve governor Kconfig options)
the best cpuidle governor is selected automatically. There is little
point in additionally selecting the other one as it will not be used,
so don't select both governors by default.

Being able to select more than one governor is still good for
developers booting with cpuidle_sysfs_switch, though.

This fixes the second half of kernel BZ #65531.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=65531
Signed-off-by: Jean Delvare 
Signed-off-by: Rafael J. Wysocki