On Fri, Feb 09, 2018 at 03:07:00PM -0800, Raghavendra Rao Ananta wrote: > Perf framework doesn't allow creation of hardware events if > the requested CPU is offline. However, creation of an event > is achievable if the event is attached to the PMU as soon > as the CPU is online again. > > So, introducing a feature that could allow to create events > even when the CPU is offline and return a success to the caller. > If, during the time of event creation, the CPU is found offline, > the event is moved to a new state (PERF_EVENT_STATE_DORMANT). As > and when the CPU is know to be woken up (through hotplug notifiers), > all the dormant events would be attached to the PMU (by > perf_install_in_context()). If during the life time of the event, > the CPU hasn't come online, the dormant event would just be freed.
This is horrible.. and you seem to have forgotten to explain why you care about offline CPUs.
