Date: Wed, 1 Feb 2023 11:26:24 -0500 From: Paul Mather <paul@gromit.dlib.vt.edu> To: Marek Zarychta <zarychtam@plan-b.pwste.edu.pl> Cc: stable@freebsd.org Subject: Re: Slow WAN traffic to FreeBSD hosts but not to Linux hosts---how to debug/fix? Message-ID: <8AE3B49C-6C7F-4A20-B2DC-0D4B1343FB59@gromit.dlib.vt.edu> In-Reply-To: <2ed582b9-b544-74bb-2047-99d04924b46b@plan-b.pwste.edu.pl> References: <95EDCFCA-7E3F-458F-85A6-856D606B9D98@gromit.dlib.vt.edu> <4ed8b724-041f-f561-ae60-ab966aefbb68@plan-b.pwste.edu.pl> <282AF730-E5E0-4A50-9F47-E7301B36E5C8@gromit.dlib.vt.edu> <2ed582b9-b544-74bb-2047-99d04924b46b@plan-b.pwste.edu.pl>
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On Jan 31, 2023, at 3:38 PM, Marek Zarychta = <zarychtam@plan-b.pwste.edu.pl> wrote: > W dniu 31.01.2023 o 19:31, Paul Mather pisze: >>> While playing with different mod_cc(4) might bring some improvement, = to get a real boost I'd suggest enabling tcp_rack(4) if feasible. >>=20 >> I am interested in trying this out, but believe it is more feasible = in my case for the -STABLE and -CURRENT systems I am using, not so much = for the -RELEASE systems that are kept up to date via binary = freebsd-update updates. My reading of the tcp_rack(4) man page is that = you have to build a custom kernel as, unlike the cc_* congestion control = algorithms, the loadable tcp_rack module is not built by default. Is = that an accurate reading? >>=20 > Yes, this gift from Netflix is probably better suited for -STABLE and = -CURRENT as easier to set up there. There is an excellent, up-to-date = article about it by Klara Systems writers[1]. =46rom my experience = tcp_rack(4) is well suited for congested, lossy or redundant network = paths where loses, duplicated packets or races between packets occur. = Not a panacea, but very performant TCP stack based on the _fair_ = algorithm. In some instances, it might help you to saturate the = bandwidth of the link. TCP algo can be loaded/unloaded/changed on the = fly. In FreeBSD 14-CURRENT you can change it on an active socket with = tcpsso(8) utility, in FreeBSD 12 and 13 you have to restart the app = bound to the socket. > Please feel free to play with TCP stacks and congestion algos with the = help of benchmarks/iperf3 to find out what prevents the link from being = saturated and give us some feedback here. >=20 > [1] = https://klarasystems.com/articles/using-the-freebsd-rack-tcp-stack/ Thank you, Marek, for the link to the Klara article about building and = using RACK. I'm building it now on a FreeBSD-CURRENT system and will = test it out. Cheers, Paul.
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