finding optimal ipfw strategy

[Eugene Grosbein]

28.08.2019 3:20, Victor Gamov wrote:

>>>> hw.igb.max_interrupt_rate=32000
>>>
>>> It's about 5000-7000 per rxq
>>
>> 7000 is quite close considering it is average for quite long period (a second or seconds).
>> It can hit 8000 for some ticks easily in your case.
> 
> Eugene,  can you explain me what max_interrupt_rate means?  Calomel explain it as  "# maximum number of interrupts per second generated by single igb".  So if I increase it then more irq per sec will be generated and more context switch produced.  Why I need to increase it?

Already did in another post.

>> You should raise the limit as soon as possible. I'd advise to double it upto 16000 first
>> but if you cannot afford extra reboot better use 32000 as it's just fine for 1Gbps link.
> # sysctl hw.igb.max_interrupt_rate
> sysctl: unknown oid 'hw.igb.max_interrupt_rate'
> #
> Is it possible to set it at boot time only?

Yes, unless you patched igb(4) sources with a patch as described in by blog:
http://www.grosbein.net/freebsd/patches/igb_sysctl-11.0.diff.gz

It adds per-interface sysctls to change this on-the-fly:

dev.igb.0.max_interrupt_rate=32000
dev.igb.1.max_interrupt_rate=32000

Be warned that you still need to re-initialize the NIC to write changed value to the chip
and this will temporary stop traffic. Easiest way is to bring the interface down/up:
ifconfig igb0 down; ifconfig igb0 up

hw.igb.max_interrupt_rate is used as default value for sysctls so if you raise the limit in loader.conf,
it is used by chip on first "up" of interface at boot time.