[Cake] small cake_hash optimization?

[Pete Heist]

> On Nov 22, 2017, at 7:33 PM, Dave Taht <dave.taht at gmail.com> wrote:
> 
> On Wed, Nov 22, 2017 at 4:37 AM, Pete Heist <peteheist at gmail.com> wrote:
>> 
>> Ok, at least a little crude testing with sar:
>> 
>> https://docs.google.com/spreadsheets/d/1LKoq5NaswuHm9H1atXoZA1AhNDg6L4UYS3Pn5lCsb1I/edit#gid=0
>> 
>> ~10% less cake CPU at GigE in this case?
> 
> Divides do hurt, particularly if you can't do them out of order. But
> that seems like a lot.

Hrm, I tried a second test to make sure fairness still works (it does) but this time got a slight _negative_ result (rrul_be fair tab). So this calls into question whether or not my testing method is very good, and also whether or not the change actually helps much.

This time I used "cake unlimited besteffort dual-srchost overhead 64 mpu 84” (overheads from Sebastian, just rely on bql).

I might try again with 950mbit limiting, and ‘perf’ instead.

Also I noted that the ‘lan’ keyword seemed to adversely affect host fairness, so I stopped using it. I’ll address that separately when there’s time.

>> What’s a better tool for timing
>> kernel module functions?
> 
> Use "perf"
> 
> https://en.wikipedia.org/wiki/Perf_(Linux)

Ok, will see if I can give it a try.