On 2026-04-22 14:52:07 [-0400], Aaron Tomlin wrote: > From: Daniel Wagner <[email protected]> > > Introduce blk_mq_{online|possible}_queue_affinity, which returns the > queue-to-CPU mapping constraints defined by the block layer. This allows > other subsystems (e.g., IRQ affinity setup) to respect block layer > requirements. > > It is necessary to provide versions for both the online and possible CPU > masks because some drivers want to spread their I/O queues only across > online CPUs, while others prefer to use all possible CPUs. And the mask > used needs to match with the number of queues requested > (see blk_num_{online|possible}_queues).
Which driver uses cpu_possible_mask? This mask is assigned at boot time once the kernel figured how many CPUs are possible based on ACPI or whatever the system uses. This mask does not change. I only see drivers/scsi/lpfc/lpfc_init.c using it. Looking at cpu_possible_mask might not be the right thing. It is usually the same thing as "online" except on system where ACPI thinks that something could be added via hotplug _or_ if the admin shuts down a CPU via cpuhotplug _or_ boots with less (there a command line option for that). In case cpu_possible_mask != cpu_online_mask the intention is to allocate memory and setup irqs for the offline CPUs? > Signed-off-by: Daniel Wagner <[email protected]> > Reviewed-by: Hannes Reinecke <[email protected]> > Signed-off-by: Aaron Tomlin <[email protected]> Sebastian
