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  1. 20 Nov, 2019 1 commit
    • Daniel Lezcano's avatar
      cpuidle: Allow idle injection to apply exit latency limit · c55b51a0
      Daniel Lezcano authored 
      In some cases it may be useful to specify an exit latency limit for
the idle state to be used during CPU idle time injection.

Instead of duplicating the information in struct cpuidle_device
or propagating the latency limit in the call stack, replace the
use_deepest_state field with forced_latency_limit_ns to represent
that limit, so that the deepest idle state with exit latency within
that limit is forced (i.e. no governors) when it is set.

A zero exit latency limit for forced idle means to use governors in
the usual way (analogous to use_deepest_state equal to "false" before
this change).

Additionally, add play_idle_precise() taking two arguments, the
duration of forced idle and the idle state exit latency limit, both
in nanoseconds, and redefine play_idle() as a wrapper around that
new function.

This change is preparatory, no functional impact is expected.
Suggested-by: default avatarRafael J. Wysocki <rafael@kernel.org>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
[ rjw: Subject, changelog, cpuidle_use_deepest_state() kerneldoc, whitespace ]
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      c55b51a0
  3. 19 Nov, 2019 1 commit
  5. 14 Nov, 2019 1 commit
  7. 13 Nov, 2019 2 commits
    • Rafael J. Wysocki's avatar
      cpuidle: teo: Avoid using "early hits" incorrectly · 63f202e5
      Rafael J. Wysocki authored 
      If the current state with the maximum "early hits" metric in
teo_select() is also the one "matching" the expected idle duration,
it will be used as the candidate one for selection even if its
"misses" metric is greater than its "hits" metric, which is not
correct.

In that case, the candidate state should be shallower than the
current one and its "early hits" metric should be the maximum
among the idle states shallower than the current one.

To make that happen, modify teo_select() to save the index of
the state whose "early hits" metric is the maximum for the
range of states below the current one and go back to that state
if it turns out that the current one should be rejected.

Fixes: 159e4856 ("cpuidle: teo: Fix "early hits" handling for disabled idle states")
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      63f202e5
    • Rafael J. Wysocki's avatar
      cpuidle: teo: Exclude cpuidle overhead from computations · b6495b7f
      Rafael J. Wysocki authored 
      One purpose of the computations in teo_update() is to determine
whether or not the (saved) time till the next timer event and the
measured idle duration fall into the same "bin", so avoid using
values that include the cpuidle overhead to obtain the latter.
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      b6495b7f
  9. 11 Nov, 2019 1 commit
    • Rafael J. Wysocki's avatar
      cpuidle: Use nanoseconds as the unit of time · c1d51f68
      Rafael J. Wysocki authored 
      Currently, the cpuidle subsystem uses microseconds as the unit of
time which (among other things) causes the idle loop to incur some
integer division overhead for no clear benefit.

In order to allow cpuidle to measure time in nanoseconds, add two
new fields, exit_latency_ns and target_residency_ns, to represent the
exit latency and target residency of an idle state in nanoseconds,
respectively, to struct cpuidle_state and initialize them with the
help of the corresponding values in microseconds provided by drivers.
Additionally, change cpuidle_governor_latency_req() to return the
idle state exit latency constraint in nanoseconds.

Also meeasure idle state residency (last_residency_ns in struct
cpuidle_device and time_ns in struct cpuidle_driver) in nanoseconds
and update the cpuidle core and governors accordingly.

However, the menu governor still computes typical intervals in
microseconds to avoid integer overflows.
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarDoug Smythies <dsmythies@telus.net>
Tested-by: default avatarDoug Smythies <dsmythies@telus.net>
      c1d51f68
  11. 06 Nov, 2019 1 commit
    • Rafael J. Wysocki's avatar
      cpuidle: Consolidate disabled state checks · 99e98d3f
      Rafael J. Wysocki authored 
      There are two reasons why CPU idle states may be disabled: either
because the driver has disabled them or because they have been
disabled by user space via sysfs.

In the former case, the state's "disabled" flag is set once during
the initialization of the driver and it is never cleared later (it
is read-only effectively).  In the latter case, the "disable" field
of the given state's cpuidle_state_usage struct is set and it may be
changed via sysfs.  Thus checking whether or not an idle state has
been disabled involves reading these two flags every time.

In order to avoid the additional check of the state's "disabled" flag
(which is effectively read-only anyway), use the value of it at the
init time to set a (new) flag in the "disable" field of that state's
cpuidle_state_usage structure and use the sysfs interface to
manipulate another (new) flag in it.  This way the state is disabled
whenever the "disable" field of its cpuidle_state_usage structure is
nonzero, whatever the reason, and it is the only place to look into
to check whether or not the state has been disabled.
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      99e98d3f
  13. 25 Oct, 2019 1 commit
    • Yin Fengwei's avatar
      ACPI: processor_idle: Skip dummy wait if kernel is in guest · fa583f71
      Yin Fengwei authored 
      In function acpi_idle_do_entry(), an ioport access is used for
dummy wait to guarantee hardware behavior. But it could trigger
unnecessary VMexit if kernel is running as guest in virtualization
environment.

If it's in virtualization environment, the deeper C state enter
operation (inb()) will trap to hypervisor. It's not needed to do
dummy wait after the inb() call. So we could just remove the
dummy io port access to avoid unnecessary VMexit.

And keep dummy io port access to maintain timing for native
environment.
Signed-off-by: default avatarYin Fengwei <fengwei.yin@intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      fa583f71
  15. 24 Oct, 2019 2 commits
  17. 22 Oct, 2019 1 commit
  19. 20 Oct, 2019 6 commits
  21. 19 Oct, 2019 23 commits
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