[phosphor-pid-control] scaling issue
Hank Liou (劉晉翰)
Hank.Liou at quantatw.com
Mon Sep 16 18:37:07 AEST 2019
Hi Patrick,
Thanks for your help. This change does solve the issue.
Hank
>-----Original Message-----
>From: Patrick Venture [mailto:venture at google.com]
>Sent: Wednesday, September 11, 2019 1:52 AM
>To: Hank Liou (劉晉翰) <Hank.Liou at quantatw.com>
>Cc: James Feist <james.feist at linux.intel.com>; openbmc at lists.ozlabs.org
>Subject: Re: [phosphor-pid-control] scaling issue
>
>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/75eb769d35143
>> > 4547899186f73ff70ae00d7934a, 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%9
>> > 3&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/+/25
>> 070
>
>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
>> > > >>>>> bounces+Of Hank 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
>> > > >>>>> info->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/fancont
>> > > >ro
>> > > >>>>> 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/fancont
>> > > >ro
>> > > >>>>> lle
>> > > >>>>> r.cpp#L64
>> > > >>>>> [6] https://github.com/openbmc/phosphor-pid-
>> > > >>>>>
>> > >
>>control/blob/a7ec8350d17b70153cebe666d3fbe88bddd02a1a/dbus/dbuspa
>> > > >ss
>> > > >>>>> 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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