Date: Sat, 4 Feb 2023 13:11:57 -0500 From: Paul Mather <paul@gromit.dlib.vt.edu> To: David <2yt@gmx.com> Cc: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: Slow WAN traffic to FreeBSD hosts but not to Linux hosts---how to debug/fix? Message-ID: <ED3BEF11-4C72-441A-9216-9D84D4E73ACD@gromit.dlib.vt.edu> In-Reply-To: <cebab4bd-ff1e-fb8d-cdc2-8720da9fd31a@gmx.com> 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> <8AE3B49C-6C7F-4A20-B2DC-0D4B1343FB59@gromit.dlib.vt.edu> <83E43236-60F8-4949-8840-54E66D327EE9@gromit.dlib.vt.edu> <d890e3c5-9570-80ed-15b4-207e47ecc614@plan-b.pwste.edu.pl> <BE435158-34CD-4A54-870E-481A6646D4DE@gromit.dlib.vt.edu> <cebab4bd-ff1e-fb8d-cdc2-8720da9fd31a@gmx.com>
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On Feb 1, 2023, at 5:54 PM, David <2yt@gmx.com> wrote: > On 2/1/23 14:07, Paul Mather wrote: >> On Feb 1, 2023, at 3:14 PM, Marek Zarychta = <zarychtam@plan-b.pwste.edu.pl> wrote: >>> W dniu 1.02.2023 o 20:33, Paul Mather pisze: >>>> It looks like we may have a winner, folks. I built and enabled the = extra TCP stacks and for the first time was able to max out my = connection to the remote FreeBSD system. I get consistently higher = throughput over the 15-hop WAN path to the remote FreeBSD system when = using the RACK TCP stack than when using the default "freebsd" stack. >>>>=20 >>>> Although the speeds are consistently higher when using the setting = "net.inet.tcp.functions_default=3Drack", they are still variable. = However, rather than the 3--4 MB/s I saw that kicked off this thread, I = now average over 10 MB/s. >>>>=20 >>>> I actually get the best results with = "net.inet.tcp.functions_default=3Dbbr" (having loaded tcp_bbr). That = behaves very much like the Linux hosts in that speeds climb very quickly = until it saturates the WAN connection. I get the same high speeds from = the remote FreeBSD system using tcp_bbr as I do to the Linux hosts. I = will stick with tcp_bbr for now as the default on my remote FreeBSD = servers. It appears to put them on a par with Linux for this WAN link. >>>=20 >>> Thanks for the feedback Paul. Please bear in mind that BBR 1 which = is implemented in FreeBSD is not a fair[1] congestion control algorithm. = Maybe in the future, we will have BBR v2 in the stack, but for now, I = don't recommend using BBR, unless you want to act slightly as a hm.... = network leecher. Maybe Linux hosts behave this way, maybe they have = implemented BBR v2, I am not familiar with Linux TCP stack enhancements. = On the other hand, tcp_rack(4) is performant, well-tested in the FreeBSD = stack, considered fair and more acceptable for a fileserver, though not = ideal, ie. probably more computationally expensive and still missing = some features like TCP-MD5. >>>=20 >>> [1] https://www.mdpi.com/1424-8220/21/12/4128 >>>=20 >> That is a fair and astute observation, Marek. I am also not familiar = with Linux TCP stack implementations but it had occurred to me that = maybe Linux was not being an entirely good netizen whereas FreeBSD was = behaving with impeccable net manners when it came to congestion control = and being fair to others, and that is why Linux was getting faster = speeds for me. Then again, perhaps not. :-) >> In the case of the remote FreeBSD hosts I use at $JOB, they have low = numbers of users and so are more akin to endpoints than servers, so I'm = not worried about "leeching" from them. Also, my ISP download bandwidth = is 1/5th of each FreeBSD system, so hopefully there is still plenty to = go around after I max out my bulk downloads. (Plus, I believe $JOB = prefers my downloads to take half [or less] the time.) :-) >> Hopefully we will get BBR v2 (or something even fairer) at some = point. IIRC, the FreeBSD Foundation has been highlighting some of this = network stack work. It would be a pity for it not to be enabled by = default so more people could use it on -RELEASE without building a = custom kernel. I'm just glad right now I'm not stuck with 3--4 MB/s = downloads any more. >> Cheers, >> Paul. >=20 > Word of caution: >=20 > It would appear not all FreeBSD applications like BBR or RACK. I run a = Magento (e-commerce) VM and was getting weird pauses (hang for a bit = then resume) on the website. Running Magneto requires several other TCP = services and something wasn't happy. Not going to debug the problem, = just wanted to give a heads up. Thanks for the heads-up. Since posting the above I have also noticed = that BBR and RACK aren't unalloyed successes for me. In my experience, = I would also notice pauses and lockups/disconnections to FreeBSD systems = with BBR enabled. I only noticed pauses with RACK on some systems in my = testing, so that was much more usable. The problems I experienced were worst on 13.1-RELEASE. A 13.1-RELEASE = system I built and enabled BBR on was almost unusable to me. RACK was = better but also had issues. Much better in my tests is BBR and RACK on = 13-STABLE and -CURRENT. I had no issues with RACK (other with more = speed variability vs BBR), whereas BBR did lock up one of my FreeBSD = clients in testing. (That client uses a RealTek re NIC, so maybe BBR = tickles more bugs in that.) RACK caused no lockups and yielded good = enough speeds for it to be my go-to combo now over BBR. I figure the better results with enabling BBR and RACK on -STABLE and = -CURRENT vs -RELEASE servers reflects potential improvements/bug fixes = in the implementation since -RELEASE landed. (Disclaimer: the -RELEASE = test system uses em NICs whereas the -STABLE and -CURRENT systems I used = in testing use igb NICs, so maybe that is a factor?) Cheers, Paul.
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