[PATCH V3 0/5] genirq/affinity: add .calc_sets for improving IRQ allocation & spread

From: Ming Lei
Date: Wed Feb 13 2019 - 05:50:59 EST


Currently pre-caculated set vectors are provided by driver for
allocating & spread vectors. This way only works when drivers passes
same 'max_vecs' and 'min_vecs' to pci_alloc_irq_vectors_affinity(),
also requires driver to retry the allocating & spread.

As Bjorn and Keith mentioned, the current usage & interface for irq sets
is a bit awkward because the retrying should have been avoided by providing
one resonable 'min_vecs'. However, if 'min_vecs' isn't same with
'max_vecs', number of the allocated vectors is unknown before calling
pci_alloc_irq_vectors_affinity(), then each set's vectors can't be

Add a new callback of .calc_sets into 'struct irq_affinity' so that
driver can caculate set vectors after IRQ vector is allocated and
before spread IRQ vectors.

- don't mark 'affd' as const in related functions
- add sanity check on affd->nr_sets
- remove the local variable of 'nr_sets' in irq_create_affinity_masks
- set .nr_sets as 2 in nvme
- update comment in msi.c

- add .calc_sets instead of .setup_affinity() which is easy to
be abused by drivers

Ming Lei (5):
genirq/affinity: don't mark 'affd' as const
genirq/affinity: store irq set vectors in 'struct irq_affinity'
genirq/affinity: add new callback for caculating set vectors
nvme-pci: avoid irq allocation retrying via .calc_sets
genirq/affinity: Document .calc_sets as required in case of multiple

drivers/nvme/host/pci.c | 63 ++++++++++++-----------------------------------
drivers/pci/msi.c | 34 ++++++++++++++-----------
include/linux/interrupt.h | 13 +++++++---
include/linux/pci.h | 4 +--
kernel/irq/affinity.c | 26 ++++++++++++-------
5 files changed, 64 insertions(+), 76 deletions(-)