lisa.tests.scheduler.load_tracking: Remove the XTask(s)CPUMigration class hierarchy
lisa.tests.scheduler.load_tracking: Remove the XTask(s)CPUMigration class hierarchy

The XTask(s)CPUMigration.test_util_task_migration() tests don't run
reliably. This is due to how the comparison between the task_util_avg
and cpu_util_avg signals is done.

The tests compare the sum(avg(task_util_avg)) for all tasks (1,2) based
on duty cycle using task activation trace events against
avg(cpu_util_avg) from a custom average function (kernel_util_mean())
using PELT trace events.

This often fails since the averaging is done over the entire
cpu_util_avg signal.

The actual migration of task migr-0 is not tested.

What should be done instead is to compare task_util_avg from the PELT
simulation against the kernel cpu_util_avg using PELT trace events
sample by sample and summarize the error (error = abs(simulated -
kernel) with avg and max error).

The tests should be replaced by a cpu_util_avg version of the
Invariance.test_util_correctness() test.

Signed-off-by: Dietmar Eggemann <b09ca079358248c3ff5bd91ea3781c6808cc6cf2@arm.com>

credp/lisa,credp/lisa,credp/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,ARM-software/lisa,ARM-software/lisa