On Sun, 17 Feb 2019, Ming Lei wrote: > On Sat, Feb 16, 2019 at 06:13:13PM +0100, Thomas Gleixner wrote: > > Some drivers need an extra set of interrupts which should not be marked > > managed, but should get initial interrupt spreading. > > Could you share the drivers and their use case? You were Cc'ed on that old discussion: https://lkml.kernel.org/r/300d6fef733ca76ced581f8c6304bac6@xxxxxxxxxxxxxx > > For both interrupt sets the interrupts are properly spread out, but the > > second set is not marked managed. > > Given drivers only care the managed vs non-managed interrupt numbers, > just wondering why this case can't be covered by .pre_vectors & > .post_vectors? Well, yes, but post/pre are not subject to spreading and I really don't want to go there. > Also this kind of usage may break blk-mq easily, in which the following > rule needs to be respected: > > 1) all CPUs are required to spread among each interrupt set > > 2) no any CPU is shared between two IRQs in same set. I don't see how that would break blk-mq. The unmanaged set is not used by the blk-mq stuff, that's some driver internal voodoo. So blk-mq still gets a perfectly spread and managed interrupt set for the queues. > > for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) { > > - unsigned int this_vecs = affd->set_size[i]; > > + bool managed = affd->unmanaged_sets & (1U << i) ? true : false; > > The above check is inverted. Doh. Stupid me. Thanks, tglx
