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  1. 13 Nov, 2019 1 commit
  3. 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
  5. 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
  7. 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
  9. 24 Oct, 2019 2 commits
  11. 22 Oct, 2019 1 commit
  13. 20 Oct, 2019 6 commits
  15. 19 Oct, 2019 27 commits
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