Re: Request for Testing: TCP RACK

> On Nov 19, 2023, at 2:35 AM, Zhenlei Huang <zlei@FreeBSD.org> wrote:
> 
> 
> 
>> On Nov 16, 2023, at 5:13 PM, tuexen@freebsd.org wrote:
>> 
>> Dear all,
>> 
>> recently the main branch was changed to build the TCP RACK stack
>> which is a loadable kernel module, by default:
>> https://cgit.FreeBSD.org/src/commit/?id=3a338c534154164504005beb00a3c6feb03756cc
>> 
>> As discussed on the bi-weekly transport call, it would be great if people
>> could test the RACK stack for their workload. Please report any problems to the
>> net@ mailing list or open an issue in the bug tracker and drop me a note via email.
>> This includes regressions in CPU usage, regressions in performance or any other
>> unexpected change you observe.
> 
> I see some performance regression with the rack stack.
> 
> This is iperf3 test on local host (bare metal, an old i5 2 cores 4 threads MBP).
> 
> freebsd:	16.1 Gbits/sec
> rack:	12.3 Gbits/sec
> 
> The congestion control algorithm is cubic.
> 
> Note this is a quick test with DEBUG options enabled.
> 
> I'll try with no debug options and report later.

** UPDATE **

With no debug options:

freebsd:	37.2 Gbits/sec
rack:	27.9 Gbits/sec

> 
>> 
>> You can load the kernel module using
>> kldload tcp_rack
>> 
>> You can make the RACK stack the default stack using
>> sysctl net.inet.tcp.functions_default=rack
>> 
>> Based on the feedback we get, the default stack might be switched to the
>> RACK stack.
>> 
>> Please let me know if you have any questions.
>> 
>> Best regards
>> Michael
>> 
>> 
>> 
> 
> Best regards,
> Zhenlei