Re: Request for Testing: TCP RACK

From: Mike Karels <mike_at_karels.net>
Date: Mon, 18 Mar 2024 12:26:10 UTC 
On 18 Mar 2024, at 7:04, tuexen@freebsd.org wrote:

>> On 18. Mar 2024, at 12:42, Nuno Teixeira <eduardo@freebsd.org> wrote:
>>
>> Hello all!
>>
>> It works just fine!
>> System performance is OK.
>> Using patch on main-n268841-b0aaf8beb126(-dirty).
>>
>> ---
>> net.inet.tcp.functions_available:
>> Stack                           D Alias                            PCB count
>> freebsd                           freebsd                          0
>> rack                            * rack                             38
>> ---
>>
>> It would be so nice that we can have a sysctl tunnable for this patch
>> so we could do more tests without recompiling kernel.
> Thanks for testing!
>
> @gallatin: can you come up with a patch that is acceptable for Netflix
> and allows to mitigate the performance regression.

Ideally, tcphpts could enable this automatically when it starts to be
used (enough?), but a sysctl could select auto/on/off.

		Mike

> Best regards
> Michael
>>
>> Thanks all!
>> Really happy here :)
>>
>> Cheers,
>>
>> Nuno Teixeira <eduardo@freebsd.org> escreveu (domingo, 17/03/2024 à(s) 20:26):
>>>
>>> Hello,
>>>
>>>> I don't have the full context, but it seems like the complaint is a performance regression in bonnie++ and perhaps other things when tcp_hpts is loaded, even when it is not used.  Is that correct?
>>>>
>>>> If so, I suspect its because we drive the tcp_hpts_softclock() routine from userret(), in order to avoid tons of timer interrupts and context switches.  To test this theory,  you could apply a patch like:
>>>
>>> It's affecting overall system performance, bonnie was just a way to
>>> get some numbers to compare.
>>>
>>> Tomorrow I will test patch.
>>>
>>> Thanks!
>>>
>>> --
>>> Nuno Teixeira
>>> FreeBSD Committer (ports)
>>
>>
>>
>> -- 
>> Nuno Teixeira
>> FreeBSD Committer (ports)