[phosphor-pid-control] scaling issue
Patrick Venture
venture at google.com
Wed Sep 11 03:52:24 AEST 2019
On Tue, Sep 10, 2019 at 7:52 AM Patrick Venture <venture at google.com> wrote:
>
> On Tue, Sep 10, 2019 at 7:39 AM Patrick Venture <venture at google.com> wrote:
> >
> > On Tue, Sep 10, 2019 at 1:02 AM Hank Liou (劉晉翰) <Hank.Liou at quantatw.com> wrote:
> > >
> > > >-----Original Message-----
> > > >From: James Feist [mailto:james.feist at linux.intel.com]
> > > >Sent: Tuesday, September 10, 2019 1:27 AM
> > > >To: Patrick Venture <venture at google.com>; Hank Liou (劉晉翰)
> > > ><Hank.Liou at quantatw.com>
> > > >Cc: openbmc at lists.ozlabs.org
> > > >Subject: Re: [phosphor-pid-control] scaling issue
> > > >
> > > >On 9/9/19 9:57 AM, Patrick Venture wrote:
> > > >> On Thu, Sep 5, 2019 at 12:25 AM Hank Liou (劉晉翰)
> > > ><Hank.Liou at quantatw.com> wrote:
> > > >>>
> > > >>> Hi Patrick,
> > > >>>
> > > >>>
> > > >>> Sorry for not clearly stating our problem. We have the following issue:
> > > >>>
> > > >>>
> > > >>> temp sensor gets 31(C) -> 31 / 0.255 = 121.57 -> pid uses 127.57 as
> > > >>> input for temp sensor ->
> > > >>>
> > > >>> stepwise fan table output 100 duty -> full speed fan
> > > >>
> > > >> Ok, so you're getting a dbus-based min/max value and you want to
> > > >> ignore it?
> > >
> > > Yes, we want to ignore it.
> >
> > It looks like the sensor value scaling should be ignored for non-fans.
> > Per https://github.com/openbmc/phosphor-pid-control/commit/75eb769d351434547899186f73ff70ae00d7934a,
> > this change was only meant to deal with a fan case where the goal
> > looks like it was to treat the fan values as percentages on reading
> > the sensors, and not only on writing them by leveraging the min/max
> > json sometimes?
> >
> > I can change the dbuspassive constructor to set the values back to
> > their input values (ignoring dbus) if the type is not "fan", but I'm
> > not sure that makes sense because the real use-case isn't clear to me,
> > and I know the scaling from dbus is gone:
> > https://github.com/openbmc/phosphor-pid-control/search?utf8=%E2%9C%93&q=inheritValueFromDbus&type=
> >
> > I'll submit the patch real quick, but I'm not sure it's the right
> > long-term fix. I'd like to clean this up if possible so that we don't
> > leverage "unused" features of a configuration and instead explicitly
> > use them (or not).
>
> This patch should address what you're seeing. Overall, I think there
> should be a larger change addressing the goal of the original change.
>
> https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-pid-control/+/25070
I decided to take on the larger change because chances are we might
hit it some other way:
https://gerrit.openbmc-project.xyz/c/25072/
This lets you specify a json configuration option that will ignore the
MinValue/MaxValue properties on dbus.
>
> >
> > >
> > > >
> > > >What is providing the dbus-based min/max?
> > >
> > > We use dbus min/max for phosphor-sel-logger utility. The dbus min/max is provided by config file of phosphor-hwmon.
> > > In our case, they are -128/127 respectively.
> > >
> > > I have an observation:
> > > I found that while fan readpath is of the form "/sys/...", the fan input would not be rescaled. The same is for other sensors since the input value would not enter rescaling function.
> > > However, in our case we don't have a sys path for some thermal sensors.
> > >
> > > >
> > > >> In the json configuration, if you set the values to 0, they are set to
> > > >> the default (0), so there'd be no clean way to know to ignore dbus in
> > > >> this case, without adding a small check to only consider min/max from
> > > >> dbus when sensor is not temp/margin. Basically, only care about
> > > >> min/max on dbus if type is "fan"
> > > >
> > >
> > > I agree with the option to add a check since the min/max is only for fan now.
> > >
> > > >Why is the dbus-based min/max even there if you don't plan on using it?
> > > >
> > > >>
> > > >> If that's right, James do you have a cycle to look at this one-liner?
> > > >>
> > > >>>
> > > >>>
> > > >>> As a result, fan will be at full speed while temp is low. Before the commit
> > > >fc2e803 [1], this won't happen. The root cause is that, before fc2e803, pid will
> > > >use config min/max, which is 0 in our case. This would not trigger scaling
> > > >function, namely scaleSensorReading, in util.cpp. However, after such commit,
> > > >min/max would be non-zero (-128/127 from DBus). This will trigger scaling
> > > >function.
> > > >>>
> > > >>>
> > > >>> [1]
> > > >>> https://github.com/openbmc/phosphor-pid-
> > > >control/commit/fc2e803f5d9256
> > > >>> 944e18c7c878a441606b1f121c
> > > >>>
> > > >>>
> > > >>> Hank
> > > >>>
> > > >>>
> > > >>> ________________________________
> > > >>> From: Hank Liou (劉晉翰)
> > > >>> Sent: Monday, September 2, 2019 4:52 PM
> > > >>> To: Patrick Venture
> > > >>> Cc: James Feist; openbmc at lists.ozlabs.org
> > > >>> Subject: Re: [phosphor-pid-control] scaling issue
> > > >>>
> > > >>>
> > > >>> Hi Patrick,
> > > >>>
> > > >>>
> > > >>> Since we use phosphor-sel-logger [1] at the same time, we do assign min
> > > >and max of temp sensors to Dbus (max: 127, min: -128). So in the present case,
> > > >our temp value will be divided by 0.255 (also due to exponent is -3 here). This
> > > >will cause re-scaling problem. Therefore there should be an statement to
> > > >distinguish sensor types. If it is "temp", then one assigns 0 to the min and max
> > > >from Dbus.
> > > >>>
> > > >>>
> > > >>> [1]
> > > >>> https://github.com/openbmc/phosphor-sel-
> > > >logger/blob/3d300fca24b30864b
> > > >>> 3e9a4f5768cfe5e769458ae/include/sensorutils.hpp#L59
> > > >>>
> > > >>>
> > > >>> Hank
> > > >>>
> > > >>>
> > > >>> ________________________________
> > > >>> From: Patrick Venture <venture at google.com>
> > > >>> Sent: Friday, August 30, 2019 1:47 AM
> > > >>> To: Hank Liou (劉晉翰)
> > > >>> Cc: James Feist; openbmc at lists.ozlabs.org
> > > >>> Subject: Re: [phosphor-pid-control] scaling issue
> > > >>>
> > > >>> PTAL - https://gerrit.openbmc-project.xyz/24827 - this is merged, and
> > > >>> the srcrev bump should propagate into openbmc/openbmc in a day or two.
> > > >>>
> > > >>> On Wed, Aug 28, 2019 at 11:00 PM Hank Liou (劉晉翰)
> > > ><Hank.Liou at quantatw.com> wrote:
> > > >>>>
> > > >>>> Hi Patrick,
> > > >>>>
> > > >>>> I think it's OK to parse the config min&max for temp sensors.
> > > >>>>
> > > >>>> Any suggestion?
> > > >>>>
> > > >>>> Thanks,
> > > >>>> Hank
> > > >>>>
> > > >>>>> -----Original Message-----
> > > >>>>> From: openbmc [mailto:openbmc-
> > > >>>>> bounces+hank.liou=quantatw.com at lists.ozlabs.org] On Behalf Of Hank
> > > >>>>> bounces+Liou
> > > >>>>> (劉晉翰)
> > > >>>>> Sent: Friday, August 23, 2019 4:31 PM
> > > >>>>> To: Patrick Venture <venture at google.com>; James Feist
> > > >>>>> <james.feist at linux.intel.com>
> > > >>>>> Cc: openbmc at lists.ozlabs.org
> > > >>>>> Subject: RE: [phosphor-pid-control] scaling issue
> > > >>>>>
> > > >>>>> Hi Patrick,
> > > >>>>>
> > > >>>>>> -----Original Message-----
> > > >>>>>> From: Patrick Venture [mailto:venture at google.com]
> > > >>>>>> Sent: Wednesday, August 21, 2019 10:32 PM
> > > >>>>>> To: Hank Liou (劉晉翰) <Hank.Liou at quantatw.com>; James Feist
> > > >>>>>> <james.feist at linux.intel.com>
> > > >>>>>> Cc: openbmc at lists.ozlabs.org
> > > >>>>>> Subject: Re: [phosphor-pid-control] scaling issue
> > > >>>>>>
> > > >>>>>> On Wed, Aug 21, 2019 at 1:11 AM Hank Liou (劉晉翰)
> > > >>>>>> <Hank.Liou at quantatw.com> wrote:
> > > >>>>>>>
> > > >>>>>>> Hi All,
> > > >>>>>>>
> > > >>>>>>>
> > > >>>>>>> After commit [1], I found my temp sensor reading would be
> > > >>>>>>> re-scaled by
> > > >>>>>> multiplying 1 over 255, making temperature into unfamiliar unit.
> > > >>>>>> Also the fan rpm reading would lie in [0,1] interval, letting the
> > > >>>>>> fan input to be 0 (since the input value of fan is from an integer
> > > >>>>>> array [2]). Are these
> > > >>>>> normal behaviors?
> > > >>>>>> Or do I miss something?
> > > >>>>>>
> > > >>>>>> Are you using dbus configuration or json? If json, can you attach your
> > > >config.
> > > >>>>>> Since you're saying it was working and now isn't, I'm assuming
> > > >>>>>> there's something about the config being treated differently with
> > > >>>>>> the code changes in an unexpected way.
> > > >>>>>
> > > >>>>> I found pid control will first read min and max from dbus and then
> > > >>>>> (before commit [1]) revise them if
> > > >>>>>
> > > >>>>> info->min != conf::inheritValueFromDbus (in dbus/dbuspassive.cpp)
> > > >>>>>
> > > >>>>> After value initialization, the min and max would be the ones in
> > > >>>>> json file (Json file [3]). However, after commit [1] the min and
> > > >>>>> max values of config would not be fed into the fan control process.
> > > >>>>> The scaling issue is originated from commit [4] with the aim to
> > > >>>>> treat fan rpm as percentage. It seems that commit [1] unexpectedly
> > > >>>>> affects temp sensors in the sense that the temp is the integer
> > > >>>>> reading not percentage. Before commit [1], it would not re-scale the
> > > >temp reading since my min and max are 0 [6].
> > > >>>>>
> > > >>>>>
> > > >>>>>
> > > >>>>> There is another issue with commit [1]. Now the fan rpm would be
> > > >>>>> something like
> > > >>>>>
> > > >>>>> 1500 / 20000 = 0.075
> > > >>>>>
> > > >>>>> where rpm max 20000 is from dbus. However the fan input function
> > > >>>>> would transfer double into int, which is 0 for 0.075 (see [5]).
> > > >>>>> Hence the fan input is 0 not percentage. Is there something wrong?
> > > >>>>>
> > > >>>>> [1] https://github.com/openbmc/phosphor-pid-
> > > >>>>> control/commit/fc2e803f5d9256944e18c7c878a441606b1f121c
> > > >>>>> [2] https://github.com/openbmc/phosphor-pid-
> > > >>>>>
> > > >control/blob/a7ec8350d17b70153cebe666d3fbe88bddd02a1a/pid/fancontro
> > > >>>>> lle
> > > >>>>> r.cpp#L86
> > > >>>>> [3]
> > > >>>>> {
> > > >>>>> "name": "fan1",
> > > >>>>> "type": "fan",
> > > >>>>> "readPath": "/sys/class/hwmon/hwmon1/fan1_input",
> > > >>>>> "writePath": "/sys/class/hwmon/hwmon1/pwm1",
> > > >>>>> "min": 0,
> > > >>>>> "max": 255
> > > >>>>> },
> > > >>>>> {
> > > >>>>> "name": "temp1",
> > > >>>>> "type": "temp",
> > > >>>>> "readPath":
> > > >"/xyz/openbmc_project/sensors/temperature/temp1",
> > > >>>>> "writePath": "",
> > > >>>>> "min": 0,
> > > >>>>> "max": 0
> > > >>>>> }
> > > >>>>> [4] https://github.com/openbmc/phosphor-pid-
> > > >>>>> control/commit/75eb769d351434547899186f73ff70ae00d7934a
> > > >>>>> [5] https://github.com/openbmc/phosphor-pid-
> > > >>>>>
> > > >control/blob/a7ec8350d17b70153cebe666d3fbe88bddd02a1a/pid/fancontro
> > > >>>>> lle
> > > >>>>> r.cpp#L64
> > > >>>>> [6] https://github.com/openbmc/phosphor-pid-
> > > >>>>>
> > > >control/blob/a7ec8350d17b70153cebe666d3fbe88bddd02a1a/dbus/dbuspass
> > > >>>>> i
> > > >>>>> ve.cpp#L158
> > > >>>>>
> > > >>>>>>
> > > >>>>>>>
> > > >>>>>>>
> > > >>>>>>> [1]
> > > >>>>>>> https://github.com/openbmc/phosphor-pid-
> > > >>>>>> control/commit/fc2e803f5d92569
> > > >>>>>>> 44e18c7c878a441606b1f121c
> > > >>>>>>>
> > > >>>>>>> [2]
> > > >>>>>>> https://github.com/openbmc/phosphor-pid-
> > > >>>>>> control/blob/a7ec8350d17b70153
> > > >>>>>>> cebe666d3fbe88bddd02a1a/pid/fancontroller.cpp#L86
> > > >>>>>>>
> > > >>>>>>>
> > > >>>>>>> Thanks,
> > > >>>>>>>
> > > >>>>>>>
> > > >>>>>>> Hank Liou
> > > >>>>>>>
> > > >>>>>>> Quanta Computer Inc.
> > > >>>>>>>
> > > >>>>>>>
> > > >>>>>
> > > >>>>> Sincerely,
> > > >>>>> Hank
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