Re: Request for Testing: TCP RACK

> 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.

> 
> 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