Re: [bitbake-devel][PATCH 1/2] runqueue: fix PSI check calculation

[Randy MacLeod <randy.macleod@windriver.com>]

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On 2023-04-06 23:07, Chen Qi via lists.openembedded.org wrote:
> The current PSI check calculation does not take into consideration
> the possibility of the time interval between last check and current
> check being much larger than 1s. In fact, the current behavior does
> not match what the manual says about BB_PRESSURE_MAX_XXX, even if
> the value is set to upper limit, 1000000, we still get many blocks
> on new task launch. The difference between 'total' should be divided
> by the time interval if it's larger than 1s.


Yes!
I had a patch  to do this but wanted to write a test case using stress .

Anyway, it's clearly better and won't allow the occasional new job to
slip in when the time diff is small and the pressure hasn't been 
recalculated
by the kernel. It will mean that pressure regulated builds may be a bit 
slower
but I doubt we'll even be able to measure that.

Thanks Qi,

../Randy


>
> Signed-off-by: Chen Qi<Qi.Chen@windriver.com>
> ---
>   bitbake/lib/bb/runqueue.py | 13 +++++++++----
>   1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/bitbake/lib/bb/runqueue.py b/bitbake/lib/bb/runqueue.py
> index e629ab7e7b..02f1474540 100644
> --- a/bitbake/lib/bb/runqueue.py
> +++ b/bitbake/lib/bb/runqueue.py
> @@ -198,15 +198,20 @@ class RunQueueScheduler(object):
>                   curr_cpu_pressure = cpu_pressure_fds.readline().split()[4].split("=")[1]
>                   curr_io_pressure = io_pressure_fds.readline().split()[4].split("=")[1]
>                   curr_memory_pressure = memory_pressure_fds.readline().split()[4].split("=")[1]
> -                exceeds_cpu_pressure =  self.rq.max_cpu_pressure and (float(curr_cpu_pressure) - float(self.prev_cpu_pressure)) > self.rq.max_cpu_pressure
> -                exceeds_io_pressure =  self.rq.max_io_pressure and (float(curr_io_pressure) - float(self.prev_io_pressure)) > self.rq.max_io_pressure
> -                exceeds_memory_pressure = self.rq.max_memory_pressure and (float(curr_memory_pressure) - float(self.prev_memory_pressure)) > self.rq.max_memory_pressure
>                   now = time.time()
> -                if now - self.prev_pressure_time > 1.0:
> +                tdiff = now - self.prev_pressure_time
> +                if tdiff > 1.0:
> +                    exceeds_cpu_pressure =  self.rq.max_cpu_pressure and (float(curr_cpu_pressure) - float(self.prev_cpu_pressure)) / tdiff > self.rq.max_cpu_pressure
> +                    exceeds_io_pressure =  self.rq.max_io_pressure and (float(curr_io_pressure) - float(self.prev_io_pressure)) / tdiff > self.rq.max_io_pressure
> +                    exceeds_memory_pressure = self.rq.max_memory_pressure and (float(curr_memory_pressure) - float(self.prev_memory_pressure)) / tdiff > self.rq.max_memory_pressure
>                       self.prev_cpu_pressure = curr_cpu_pressure
>                       self.prev_io_pressure = curr_io_pressure
>                       self.prev_memory_pressure = curr_memory_pressure
>                       self.prev_pressure_time = now
> +                else:
> +                    exceeds_cpu_pressure =  self.rq.max_cpu_pressure and (float(curr_cpu_pressure) - float(self.prev_cpu_pressure)) > self.rq.max_cpu_pressure
> +                    exceeds_io_pressure =  self.rq.max_io_pressure and (float(curr_io_pressure) - float(self.prev_io_pressure)) > self.rq.max_io_pressure
> +                    exceeds_memory_pressure = self.rq.max_memory_pressure and (float(curr_memory_pressure) - float(self.prev_memory_pressure)) > self.rq.max_memory_pressure
>               return (exceeds_cpu_pressure or exceeds_io_pressure or exceeds_memory_pressure)
>           return False
>   
>
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-- 
# Randy MacLeod
# Wind River Linux

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