> -----Original Message----- > From: Sagi Grimberg <sagi@xxxxxxxxxxx> > Sent: Tuesday, October 23, 2018 4:25 PM > To: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx>; 'Christoph Hellwig' > <hch@xxxxxx> > Cc: linux-block@xxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx; linux- > nvme@xxxxxxxxxxxxxxxxxxx; 'Max Gurtovoy' <maxg@xxxxxxxxxxxx> > Subject: Re: [PATCH v2] block: fix rdma queue mapping > > > >>>> Christoph, Sagi: it seems you think /proc/irq/$IRP/smp_affinity > >>>> shouldn't be allowed if drivers support managed affinity. Is that > correct? > >>> > >>> Not just shouldn't, but simply can't. > >>> > >>>> But as it stands, things are just plain borked if an rdma driver > >>>> supports ib_get_vector_affinity() yet the admin changes the affinity via > >>>> /proc... > >>> > >>> I think we need to fix ib_get_vector_affinity to not return anything > >>> if the device doesn't use managed irq affinity. > >> > >> Steve, does iw_cxgb4 use managed affinity? > >> > >> I'll send a patch for mlx5 to simply not return anything as managed > >> affinity is not something that the maintainers want to do. > > > > I'm beginning to think I don't know what "managed affinity" actually is. > Currently iw_cxgb4 doesn't support ib_get_vector_affinity(). I have a patch > for it, but ran into this whole issue with nvme failing if someone changes the > affinity map via /proc. > > That means that the pci subsystem gets your vector(s) affinity right and > immutable. It also guarantees that you have reserved vectors and not get > a best effort assignment when cpu cores are offlined. > > You can simply enable it by adding PCI_IRQ_AFFINITY to > pci_alloc_irq_vectors() or call pci_alloc_irq_vectors_affinity() > to communicate post/pre vectors that don't participate in > affinitization (nvme uses it for admin queue). > > This way you can easily plug ->get_vector_affinity() to return > pci_irq_get_affinity(dev, vector) > > The original patch set from hch: > https://lwn.net/Articles/693653/ Thanks for educating me. 😊 I'll have a look into this. Steve.
