mlx5 irq

[Michal Vančo]

Hi

I have a server with one Mellanox ConnectX-4 adapter and the following
CPU configuration (SMT disabled):

# dmesg | grep SMP
FreeBSD/SMP: Multiprocessor System Detected: 16 CPUs
FreeBSD/SMP: 2 package(s) x 8 core(s) x 2 hardware threads
FreeBSD/SMP Online: 2 package(s) x 8 core(s)

What I don't understand is the number of IRQs allocated for each mlx5_core:

# vmstat -i | grep mlx5_core
irq320: mlx5_core0                     1          0
irq321: mlx5_core0              18646775         84
irq322: mlx5_core0                    21          0
irq323: mlx5_core0                 97793          0
irq324: mlx5_core0                 84685          0
irq325: mlx5_core0                 89288          0
irq326: mlx5_core0                 93564          0
irq327: mlx5_core0                 86892          0
irq328: mlx5_core0                 99141          0
irq329: mlx5_core0                 86695          0
irq330: mlx5_core0                104023          0
irq331: mlx5_core0                 85238          0
irq332: mlx5_core0                 88387          0
irq333: mlx5_core0              93310221        420
irq334: mlx5_core0               1135906          5
irq335: mlx5_core0                 85394          0
irq336: mlx5_core0                 88361          0
irq337: mlx5_core0                 88826          0
irq338: mlx5_core0              17909515         81
irq339: mlx5_core1                     1          0
irq340: mlx5_core1              18646948         84
irq341: mlx5_core1                    25          0
irq342: mlx5_core1                208684          1
irq343: mlx5_core1                 91567          0
irq344: mlx5_core1                 88340          0
irq345: mlx5_core1                 92597          0
irq346: mlx5_core1                 85108          0
irq347: mlx5_core1                 98858          0
irq348: mlx5_core1                 88103          0
irq349: mlx5_core1                104906          0
irq350: mlx5_core1                 84947          0
irq351: mlx5_core1                 99767          0
irq352: mlx5_core1               9482571         43
irq353: mlx5_core1               1724267          8
irq354: mlx5_core1                 96698          0
irq355: mlx5_core1                473324          2
irq356: mlx5_core1                 86760          0
irq357: mlx5_core1              11590861         52

I expected number of IRQs to be equal number of CPUS. According to
Mellanox docs, I should be able to pin each interrupt to specific core
to loadbalance. How can I do this in this case when number of IRQs is
larger than number of cores? Is there any way to lower the number of
interrupts?

regards

Michal