On Mon, Mar 9, 2026 at 4:55 PM Sungwoo Kim <[email protected]> wrote:
>
> On Mon, Mar 9, 2026 at 11:31 AM Caleb Sander Mateos
> <[email protected]> wrote:
> >
> > On Sun, Mar 8, 2026 at 11:30 PM Sungwoo Kim <[email protected]> wrote:
> > >
> > > The numa_node can be < 0 since NUMA_NO_NODE = -1. However,
> > > struct blk_mq_hw_ctx{} defines numa_node as unsigned int. As a result,
> > > numa_node is set to UINT_MAX for NUMA_NO_NODE in blk_mq_alloc_hctx().
> >
> > The node argument to blk_mq_alloc_hctx() comes from
> > blk_mq_alloc_and_init_hctx(), which is called by
> > blk_mq_alloc_and_init_hctx() with int node = blk_mq_get_hctx_node(set,
> > i). node = NUMA_NO_NODE would suggest that blk_mq_hw_queue_to_node()
> > doesn't find any CPU affinitized to the queue. Is that even possible?
>
> Thanks for your review, Celeb.
While I'm flattered you consider me a celebrity, my name is Caleb :)
>
> blk_mq_hw_queue_to_node() can return NUMA_NO_NODE if the device queues
> exceed the
> number of CPUs. Afterward, it is adjusted on the caller side to
> numa_node = set->numa_node.
I thought the NVMe driver capped the number of queues so every queue
is affinitized to some CPU (see nvme_max_io_queues()). What am I
missing?
Best,
Caleb
>
> set->numa_node can still be NUMA_NO_NODE if CONFIG_NUMA=n (trivial) or
> pcibus_to_node() returns NUMA_NO_NODE if ACPI doesn't provide
> proximity information.
> But I'm not sure if this is usual in the real machines. We found the
> crash in QEMU.
>
> > > static struct nvme_descriptor_pools *
> > > -nvme_setup_descriptor_pools(struct nvme_dev *dev, unsigned numa_node)
> > > +nvme_setup_descriptor_pools(struct nvme_dev *dev, int numa_node)
> > > {
> > > - struct nvme_descriptor_pools *pools =
> > > &dev->descriptor_pools[numa_node];
> > > + struct nvme_descriptor_pools *pools;
> > > size_t small_align = NVME_SMALL_POOL_SIZE;
> > >
> > > + if (numa_node == NUMA_NO_NODE)
> > > + pools = &dev->descriptor_pools[numa_node_id()];
> > > + else
> > > + pools = &dev->descriptor_pools[numa_node];
> >
> > Simpler: if (numa_node == NUMA_NO_NODE) numa_node = numa_node_id();
> >
>
> Thanks, I will modify it in V2.
>
> Sungwoo.
