Messages in this thread | | | Subject | Re: [PATCH v2] thermal: re-calculate k_po/k_pu when update sustainable power | From | Daniel Thompson <> | Date | Tue, 5 Jan 2016 18:02:57 +0000 |
| |
On 05/01/16 17:40, Punit Agrawal wrote: > Daniel Thompson <daniel.thompson@linaro.org> writes: > >> On 05/01/16 16:33, Javi Merino wrote: >>> On Mon, Jan 04, 2016 at 11:22:26AM +0000, Daniel Thompson wrote: >>>> On 01/01/16 00:03, Leo Yan wrote: >>>>> Hi Eduardo, >>>>> >>>>> Thanks for review. >>>>> >>>>> On Thu, Dec 31, 2015 at 09:21:26AM -0800, Eduardo Valentin wrote: >>>>>> On Wed, Dec 30, 2015 at 06:38:40PM +0800, Leo Yan wrote: >>>>>>> k_po/k_pu are in essence ratio values compared with sustainable power. >>>>>>> So when update sustainable power, we can recalculate k_po/k_pu simply >>>>>>> with below formula: >>>>>>> >>>>>>> sustainable_power(new) >>>>>>> k_p(new) = ---------------------- * k_p(old) >>>>>>> sustainable_power(old) >>>>>>> >>>>>>> Signed-off-by: Leo Yan <leo.yan@linaro.org> >>>>>>> --- >>>>>>> drivers/thermal/thermal_core.c | 6 +++++- >>>>>>> 1 file changed, 5 insertions(+), 1 deletion(-) >>>>>>> >>>>>>> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c >>>>>>> index d9e525c..223f8df 100644 >>>>>>> --- a/drivers/thermal/thermal_core.c >>>>>>> +++ b/drivers/thermal/thermal_core.c >>>>>>> @@ -908,7 +908,7 @@ sustainable_power_store(struct device *dev, struct device_attribute *devattr, >>>>>>> const char *buf, size_t count) >>>>>>> { >>>>>>> struct thermal_zone_device *tz = to_thermal_zone(dev); >>>>>>> - u32 sustainable_power; >>>>>>> + u32 sustainable_power, old_val; >>>>>>> >>>>>>> if (!tz->tzp) >>>>>>> return -EIO; >>>>>>> @@ -916,8 +916,12 @@ sustainable_power_store(struct device *dev, struct device_attribute *devattr, >>>>>>> if (kstrtou32(buf, 10, &sustainable_power)) >>>>>>> return -EINVAL; >>>>>>> >>>>>>> + old_val = tz->tzp->sustainable_power; >>>>>>> + >>>>>>> tz->tzp->sustainable_power = sustainable_power; >>>>>>> >>>>>>> + tz->tzp->k_po = (tz->tzp->k_po * sustainable_power) / old_val; >>>>>>> + tz->tzp->k_pu = (tz->tzp->k_pu * sustainable_power) / old_val; >>>>>> >>>>>> I believe this has to be done by the governor. These properties are >>>>>> power_allocator specific. thermal_core should not really care about >>>>>> them. >>>>> >>>>> Okay, I will try to update these properties in power_allocator.c. >>>>> Javi, do you think this is fine for you? >>>> >>>> If sustainable power were to change frequently (perhaps on >>>> entry/exit of a fan inhibitor mode?) then we would accumulate >>>> rounding errors here... >>> >>> Can you elaborate on the use case? What is this fan inhibitor mode? >> >> It's made up. >> >> I was trying to think of use cases which might result in the userspace >> wishing to make frequent changes the maximum sustainable power. For >> designs where the system remains thermally overcommited even with the >> fan running then having a mode where the fan must not spin up would >> require such a change. > > If there isn't an immediate use case, we should hold off making any > changes until they're really needed.
Fair point but do note that the fan inhibition comments were used to illustrate a bug in the patch. They were not an argument for (or against) the value of patch itself.
Daniel.
| |