Re: The irq Affinity is changed after the patch(Fixes: b1a5a73e64e9 ("genirq/affinity: Spread vectors on node according to nr_cpu ratio"))

[Ming Lei <ming.lei@redhat.com>]

On Tue, Nov 19, 2019 at 09:25:30AM +0800, chenxiang (M) wrote:
> Hi,
> 
> There are 128 cpus and 16 irqs for SAS controller in my system, and there
> are 4 Nodes, every 32 cpus are for one node (cpu0-31 for node0, cpu32-63 for
> node1, cpu64-95 for node2, cpu96-127 for node3).
> We use function pci_alloc_irq_vectors_affinity() to set the affinity of
> irqs.
> 
> I find that  before the patch (Fixes: b1a5a73e64e9 ("genirq/affinity: Spread
> vectors on node according to nr_cpu ratio")), the relationship between irqs
> and cpus is: irq0 bind to cpu0-7, irq1 bind to cpu8-15,
> irq2 bind to cpu16-23, irq3 bind to cpu24-31,irq4 bind to cpu32-39... irq15
> bind to cpu120-127. But after the patch, the relationship is changed: irq0
> bind to cpu32-39,
> irq1 bind to cpu40-47, ..., irq11 bind to cpu120-127, irq12 bind to cpu0-7,
> irq13 bind to cpu8-15, irq14 bind to cpu16-23, irq15 bind to cpu24-31.
> 
> I notice that before calling the sort() in function alloc_nodes_vectors(),
> the id of array node_vectors[] is from 0,1,2,3. But after function sort(),
> the index of array node_vectors[] is 1,2,3,0.
> But i think it sorts according to the numbers of cpus in those nodes, so it
> should be the same as before calling sort() as the numbers of cpus in every
> node are 32.

Maybe there are more non-present CPUs covered by node 0.

Could you provide the following log?

1) lscpu

2) ./dump-io-irq-affinity $PCI_ID_SAS

	http://people.redhat.com/minlei/tests/tools/dump-io-irq-affinity

You need to figure out the PCI ID(the 1st column of lspci output) of the SAS
controller via lspci.

Thanks,
Ming