ixl(4): Fix two important RSS bugs.

[erj]

Summary

• Change tc_mapping field from 0x8000 to 0x0c00; this allows RSS to hash to 64 queues instead of 16.

• Set hash_lut_size to 512 before calling filter control; the default size is 128 if that bit is not set.

Related bugzilla: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203445

Test Plan

Test using 8-64 queues (64 threads of 32 byte UDP)

[adrian]

sys/dev/ixl/if_ixl.c

2763 ↗

(On Diff #13069)

hiya,

can you comment what this mapping means? Otherwise it's just a magic constant. :)

[erj]

sys/dev/ixl/if_ixl.c

2763 ↗

(On Diff #13069)

I guess I could clarify what the 3 bits that are set here are for. But honestly, you should be reading the datasheet to find out what it does.

Until then, it means the number of queues assigned to the VSI for traffic class 0; 2^n of the value bytes/bits 1.1-1.3 is that number. I'll look to see if there's a constant defined in the shared code that I can use, or otherwise create one.

[erj]

Update with no magic number and a better comment.