Re: [docs] [PATCH] doc: bitbake-user-manual: expand description of BB_PRESSURE_MAX variables

Michael Opdenacker
2022-10-12T12:58:49Z

Hi Quentin,

On 10/12/22 14:52, Quentin Schulz via lists.yoctoproject.org wrote:
> Hi Michael, Paul,
>
> On 10/12/22 14:43, Michael Opdenacker via lists.yoctoproject.org wrote:
>> From: Michael Opdenacker <michael.opdenacker@bootlin.com>
>>
>> Signed-off-by: Paul Eggleton <paul.eggleton@microsoft.com>
>> Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
>> ---
>>   .../bitbake-user-manual-ref-variables.rst     | 60 +++++++++++++------
>>   1 file changed, 43 insertions(+), 17 deletions(-)
>>
>> diff --git
>> a/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
>> b/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
>> index 725e6c2c..b9c1b75d 100644
>> --- a/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
>> +++ b/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
>> @@ -484,29 +484,55 @@ overview of their function and contents.
>>            for it to work.
>>        :term:`BB_PRESSURE_MAX_CPU`
>> -      The threshold for maximum CPU pressure before BitBake prevents
>> the
>> -      scheduling of new tasks. Once the :term:`BB_PRESSURE_MAX_CPU`
>> threshold
>> -      is exceeded, new tasks are not started until the pressure
>> subsides to
>> -      below the threshold. If :term:`BB_PRESSURE_MAX_CPU` is not
>> set, CPU
>> -      pressure is not monitored. A threshold can be set in
>> ``conf/local.conf``
>> -      as::
>> +      Specifies a maximum CPU pressure threshold, above which BitBake's
>> +      scheduler will not start new tasks (providing there is at least
>> +      one active task). If no value is set, CPU pressure is not
>> +      monitored when starting tasks.
>> +
>> +      The pressure data is calculated based upon what (recent) Linux
>
> "recent" does not mean much. Can we remove this or get a minimal
> version number?

Very good point!
/proc/pressure was introduced in Linux 4.20
(https://kernelnewbies.org/Linux_4.20#Pressure_stall_information_for_better_overview_of_system_load)

I'm sending an update soon.
Thanks again

Michael.

--
Michael Opdenacker, Bootlin
Embedded Linux and Kernel engineering