Re: [bitbake-devel] [PATCH] runqueue: show the current pressure as debug messages

["Antonin Godard" <antonin.godard@bootlin.com>]

On Tue Jul 1, 2025 at 11:23 PM CEST, Richard Purdie wrote:
> On Tue, 2025-07-01 at 11:53 +0200, Antonin Godard via lists.openembedded.org wrote:
>> The current pressure logic only prints pressure information when the
>> limits set by BB_PRESSURE_* variables are exceeded. But in order to
>> determine the best pressure limits for a given host, it can be useful to
>> monitor pressure information after setting BB_PRESSURE_* to the maximum
>> (1000000) and get a sense of how high the pressure can be.
>> 
>> Add three bb.debug() calls showing that information.
>> 
>> Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
>> ---
>>  lib/bb/runqueue.py | 3 +++
>>  1 file changed, 3 insertions(+)
>> 
>> diff --git a/lib/bb/runqueue.py b/lib/bb/runqueue.py
>> index 80f3d3282f..cae4bfa3e5 100644
>> --- a/lib/bb/runqueue.py
>> +++ b/lib/bb/runqueue.py
>> @@ -206,6 +206,9 @@ class RunQueueScheduler(object):
>>                  cpu_pressure = (float(curr_cpu_pressure) - float(self.prev_cpu_pressure)) / tdiff
>>                  io_pressure = (float(curr_io_pressure) - float(self.prev_io_pressure)) / tdiff
>>                  memory_pressure = (float(curr_memory_pressure) - float(self.prev_memory_pressure)) / tdiff
>> +                bb.debug(3, f"Current CPU pressure: {cpu_pressure}")
>> +                bb.debug(3, f"Current IO pressure: {io_pressure}")
>> +                bb.debug(3, f"Current Memory pressure: {memory_pressure}")
>>                  exceeds_cpu_pressure =  self.rq.max_cpu_pressure and cpu_pressure > self.rq.max_cpu_pressure
>>                  exceeds_io_pressure =  self.rq.max_io_pressure and io_pressure > self.rq.max_io_pressure
>>                  exceeds_memory_pressure =  self.rq.max_memory_pressure and memory_pressure > self.rq.max_memory_pressure
>> 
>
> I'm torn on this, debug messages aren't without their overhead even if
> not printed. How often do these end up outputted? If nothing else there
> should be one bb.debug call and not 3...

Actually, quite a lot, so I should reduce this to one call, or find out a way to
reduce the amount of messages printed.

Thanks,
Antonin

-- 
Antonin Godard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com