Re: "irq 4: Affinity broken due to vector space exhaustion." warning on restart of ttyS0 console
From: Shung-Hsi Yu
Date: Wed Dec 09 2020 - 01:34:51 EST
Hi Thomas,
On Tue, Nov 10, 2020 at 09:56:27PM +0100, Thomas Gleixner wrote:
> The real problem is irqbalanced aggressively exhausting the vector space
> of a _whole_ socket to the point that there is not a single vector left
> for serial. That's the problem you want to fix.
I believe this warning also gets triggered even when there's _no_ vector
exhaustion.
This seem to happen when the IRQ's affinity mask is set (wrongly) to CPUs on
a different NUMA node (e.g. cpumask_of_node(1) when the irqd->irq == 0).
$ lscpu
...
NUMA node0 CPU(s): 0-25,52-77
NUMA node1 CPU(s): 26-51,78-103
$ cat /sys/kernel/debug/tracing/trace
...
irqbalance-1994 [017] d... 74.912799: irq_matrix_alloc: bit=33 cpu=26 online=1 avl=198 alloc=3 managed=1 online_maps=104 global_avl=20687, global_rsvd=341, total_alloc=217
irqbalance-1994 [017] d... 74.912802: vector_alloc: irq=4 vector=33 reserved=0 ret=0
irqbalance-1994 [017] d... 74.912804: vector_update: irq=4 vector=33 cpu=26 prev_vector=33 prev_cpu=7
irqbalance-1994 [017] d... 74.912805: vector_config: irq=4 vector=33 cpu=26 apicdest=0x00000040
<idle>-0 [007] d.h. 74.970733: vector_free_moved: irq=4 cpu=7 vector=33 is_managed=0
<idle>-0 [007] d.h. 74.970738: irq_matrix_free: bit=33 cpu=7 online=1 avl=200 alloc=1 managed=1 online_maps=104 global_avl=20687, global_rsvd=341, total_alloc=217
...
(agetty)-3004 [047] d... 81.731231: vector_deactivate: irq=4 is_managed=0 can_reserve=1 reserve=0
(agetty)-3004 [047] d... 81.738035: vector_clear: irq=4 vector=33 cpu=26 prev_vector=0 prev_cpu=7
(agetty)-3004 [047] d... 81.738040: irq_matrix_free: bit=33 cpu=26 online=1 avl=199 alloc=2 managed=1 online_maps=104 global_avl=20689, global_rsvd=341, total_alloc=215
(agetty)-3004 [047] d... 81.738046: irq_matrix_reserve: online_maps=104 global_avl=20689, global_rsvd=342, total_alloc=215
(agetty)-3004 [047] d... 81.766739: vector_reserve: irq=4 ret=0
(agetty)-3004 [047] d... 81.766741: vector_config: irq=4 vector=239 cpu=0 apicdest=0x00000000
(agetty)-3004 [047] d... 81.777152: vector_activate: irq=4 is_managed=0 can_reserve=1 reserve=0
(agetty)-3004 [047] d... 81.777157: vector_alloc: irq=4 vector=0 reserved=1 ret=-22
----------------------------------------> irq_matrix_alloc() failed with
EINVAL because the cpumask
passed in is empty, which is a
result of affmask being
(ff,ffffc000,000fffff,fc000000)
and cpumask_of_node(node)
being
(00,00003fff,fff00000,03ffffff).
(agetty)-3004 [047] d... 81.789349: irq_matrix_alloc: bit=33 cpu=1 online=1 avl=199 alloc=2 managed=1 online_maps=104 global_avl=20688, global_rsvd=341, total_alloc=216
(agetty)-3004 [047] d... 81.789351: vector_alloc: irq=4 vector=33 reserved=1 ret=0
(agetty)-3004 [047] d... 81.789353: vector_update: irq=4 vector=33 cpu=1 prev_vector=0 prev_cpu=26
(agetty)-3004 [047] d... 81.789355: vector_config: irq=4 vector=33 cpu=1 apicdest=0x00000002
----------------------------------------> "irq 4: Affinity broken due to
vector space exhaustion."
warning shows up
(agetty)-3004 [047] d... 81.900783: irq_matrix_alloc: bit=33 cpu=26 online=1 avl=198 alloc=3 managed=1 online_maps=104 global_avl=20687, global_rsvd=341, total_alloc=217
(agetty)-3004 [047] d... 82.053535: vector_alloc: irq=4 vector=33 reserved=0 ret=0
(agetty)-3004 [047] d... 82.053536: vector_update: irq=4 vector=33 cpu=26 prev_vector=33 prev_cpu=1
(agetty)-3004 [047] d... 82.053538: vector_config: irq=4 vector=33 cpu=26 apicdest=0x00000040
Shung-Hsi Yu