mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-01-22 16:06:04 -05:00
Code Activity

docs: thermal: convert cpu-idle-cooling.rst to ReST

Browse source 
Despite being named with .rst extension, this file doesn't
match the ReST standard. It actually causes a crash at
Sphinx:

	Sphinx parallel build error:
	docutils.utils.SystemMessage: /devel/v4l/docs/Documentation/driver-api/thermal/cpu-idle-cooling.rst:69: (SEVERE/4) Unexpected section title.

Add needed markups for it to be properly parsed.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/7640755514809a7b5fe2756f3702613865877dcb.1592203650.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mauro Carvalho Chehab 2020-06-15 08:50:07 +02:00 committed by Jonathan Corbet
parent d5ddc6d98d
commit 0c12018e01
1 changed files with 8 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

14
Documentation/driver-api/thermal/cpu-idle-cooling.rst
View file

@ -1,3 +1,5 @@
.. SPDX-License-Identifier: GPL-2.0
================ ================
CPU Idle Cooling CPU Idle Cooling
================ ================
@ -48,7 +50,7 @@ idle state target residency, we lead to dropping the static and the
dynamic leakage for this period (modulo the energy needed to enter dynamic leakage for this period (modulo the energy needed to enter
this state). So the sustainable power with idle cycles has a linear this state). So the sustainable power with idle cycles has a linear
relation with the OPP’s sustainable power and can be computed with a relation with the OPP’s sustainable power and can be computed with a
coefficient similar to: coefficient similar to::
Power(IdleCycle) = Coef x Power(OPP) Power(IdleCycle) = Coef x Power(OPP)
@ -139,7 +141,7 @@ Power considerations
-------------------- --------------------
When we reach the thermal trip point, we have to sustain a specified When we reach the thermal trip point, we have to sustain a specified
power for a specific temperature but at this time we consume: power for a specific temperature but at this time we consume::
Power = Capacitance x Voltage^2 x Frequency x Utilisation Power = Capacitance x Voltage^2 x Frequency x Utilisation
@ -148,7 +150,7 @@ wrong in the system setup). The ‘Capacitance’ and ‘Utilisation’ are a
fixed value, ‘Voltage’ and the ‘Frequency’ are fixed artificially fixed value, ‘Voltage’ and the ‘Frequency’ are fixed artificially
because we don’t want to change the OPP. We can group the because we don’t want to change the OPP. We can group the
‘Capacitance’ and the ‘Utilisation’ into a single term which is the ‘Capacitance’ and the ‘Utilisation’ into a single term which is the
‘Dynamic Power Coefficient (Cdyn)’ Simplifying the above, we have: ‘Dynamic Power Coefficient (Cdyn)’ Simplifying the above, we have::
Pdyn = Cdyn x Voltage^2 x Frequency Pdyn = Cdyn x Voltage^2 x Frequency
@ -157,7 +159,7 @@ in order to target the sustainable power defined in the device
tree. So with the idle injection mechanism, we want an average power tree. So with the idle injection mechanism, we want an average power
(Ptarget) resulting in an amount of time running at full power on a (Ptarget) resulting in an amount of time running at full power on a
specific OPP and idle another amount of time. That could be put in a specific OPP and idle another amount of time. That could be put in a
equation: equation::
P(opp)target = ((Trunning x (P(opp)running) + (Tidle x P(opp)idle)) / P(opp)target = ((Trunning x (P(opp)running) + (Tidle x P(opp)idle)) /
(Trunning + Tidle) (Trunning + Tidle)
@ -168,7 +170,7 @@ equation:
At this point if we know the running period for the CPU, that gives us At this point if we know the running period for the CPU, that gives us
the idle injection we need. Alternatively if we have the idle the idle injection we need. Alternatively if we have the idle
injection duration, we can compute the running duration with: injection duration, we can compute the running duration with::
Trunning = Tidle / ((P(opp)running / P(opp)target) - 1) Trunning = Tidle / ((P(opp)running / P(opp)target) - 1)
@ -191,7 +193,7 @@ However, in this demonstration we ignore three aspects:
target residency, otherwise we end up consuming more energy and target residency, otherwise we end up consuming more energy and
potentially invert the mitigation effect potentially invert the mitigation effect
So the final equation is: So the final equation is::
Trunning = (Tidle - Twakeup ) x Trunning = (Tidle - Twakeup ) x
(((P(opp)dyn + P(opp)static ) - P(opp)target) / P(opp)target ) (((P(opp)dyn + P(opp)static ) - P(opp)target) / P(opp)target )