Add PINNED_HARD mode for realtime hrtimers
Bugzilla: https://bugzilla.redhat.com/2203224
Upstream Status: RHEL only
Telco RAN solutions rely on timer_migration, so that most of the timers expire on housekeeping CPUs, but workloads involving FIFO tasks woken up by timers (e.g., cyclictest) requires such timers to be kept local to be able to achieve required max latencies.
RHEL8 carries a RHEL-RT only small fix that adds this special case behavior. While upstream discussion about a more general solution makes progress (last posting at https://lore.kernel.org/lkml/20230510072817.116056-1-anna-maria@linutronix.de/) we need a RHEL9 solution to meet Telco RAN requirements.
More context at https://bugzilla.redhat.com/show_bug.cgi?id=2188934#c4.
Signed-off-by: Juri Lelli juri.lelli@redhat.com
Edited by Juri Lelli