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Date:      Mon, 18 Mar 2024 07:26:10 -0500
From:      Mike Karels <mike@karels.net>
To:        tuexen@freebsd.org
Cc:        Nuno Teixeira <eduardo@freebsd.org>, Drew Gallatin <gallatin@freebsd.org>, garyj@gmx.de, current@freebsd.org, net@freebsd.org, Randall Stewart <rrs@freebsd.org>
Subject:   Re: Request for Testing: TCP RACK
Message-ID:  <6047C8EF-B1B0-4286-93FA-AA38F8A18656@karels.net>
In-Reply-To: <A3F1FC0C-C199-4565-8E07-B233ED9E7B2E@freebsd.org>
References:  <42C327BD-6CE4-43AA-A1AE-3BEC08D623DB@freebsd.org> <CAFDf7U%2BU3QpgsG-hY0u3tC_X9WKSRzuAM7Nfhzu-%2BqPBbs1nng@mail.gmail.com> <486915F0-456B-4B09-A8BC-93BBA79C4CA1@freebsd.org> <20240313080624.6c73908c@ernst.home> <508E3B47-8E1B-469F-97B1-2171A3098888@freebsd.org> <86a5n1i0xg.fsf@ltc.des.dev> <AE656D0C-FA5B-4194-8B57-4140CD57ABF1@freebsd.org> <CAFDf7UJRitdHz5QebNH9A4mNo0pKCBRfZCfmFgjNVSdCr_JXrw@mail.gmail.com> <78D1FF09-71A3-4486-B934-D8332F54B237@freebsd.org> <20240316104053.20bef8c2@ernst.home> <CAFDf7UKT=FYsaXRacwsnjDkYUjT4_1QnHynWAc67yxQS8XA0Yw@mail.gmail.com> <20240316115128.33d11f7b@ernst.home> <CAFDf7U%2BBgyw2e1hJySt-4GTX3=qn6LX7B2Ebzcmvr%2BD6MJqfpg@mail.gmail.com> <7367F29A-D52B-4828-B79A-AA2667E81E7D@freebsd.org> <CAFDf7UKRLpBt%2B11GmWO5p0b-L9ZMve6MyCxRUuVm32EBZY0MWA@mail.gmail.com> <BB57B7CC-1506-4B4C-8A04-26F67DE30EDA@freebsd.org> <CAFDf7ULtN9owoH-ns2OfR6ZhypNGxuNzkQbb2P9zR8ceFgaj5A@mail.gmail.com> <4FF534F6-B35D-4596-8D1E-226AD1347AC8@freebsd.org> <CAFDf7U%2BAjfeY%2Bqjq%2B-R71w5i1pRoxQdOmqJ9w4s1U13AA8-duA@mail.gmail.com> <C5D50314-4B0C-42F6-AA67-B5A32A4BA335@freebsd.org> <CAFDf7UKL6vtKo1Mn9Vw_5OD9Xubuw%2BdgS83WKwsiTUaXHs8D6Q@mail.gmail.com> <6e795e9c-8de4-4e02-9a96-8fabfaa4e66f@app.fastmail.com> <CAFDf7UKDWSnhm%2BTwP=ZZ9dkk0jmAgjGKPLpkX-CKuw3yH233gQ@mail.gmail.com> <CAFDf7UJq9SCnU-QYmS3t6EknP369w2LR0dNkQAc-NaRLvwVfoQ@mail.gmail.com> <A3F1FC0C-C199-4565-8E07-B233ED9E7B2E@freebsd.org>

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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 =C3=A0=
(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() routi=
ne 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)



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