Hi all, On 24.09.20 17:03, micah anderson wrote: > Oliver <bir...@sernet.de> writes: > >> Hello, >> >> after upgrading to debian buster with kernel 4.19 we also had problems. >> >> By adjusting net.ipv6.route.max_size we have fixed the following messages: >> watchdog: BUG: soft lockup - CPU#X stuck for 22s! >> and >> ixgbe 0000:02:00.0 ens2fX: initiating reset due to tx timeout >> >> But we still had a lot of jitter on the line. Downgrading to 4.9.0 fixed the >> problem, but this is not a permanent solution. >> >> What else did we tried: >> * Increasing gc_threshX >> net.ipv6.neigh.default.gc_thresh1 = 2048 >> net.ipv6.neigh.default.gc_thresh2 = 4096 >> net.ipv6.neigh.default.gc_thresh3 = 8192 >> => Did not help > > The linux kernel is getting rid of ipv6 caching, like it did with ipv4, > but it will take some time to get there. It seems that in this kernel > they have set a small value for net.ipv6.route.max_size (4096!), and > when this parameter is increased (e.g. 1048576).... the problem went > away for us. > > I'm not 100% clear on what units this value is, I had around 89k ipv6 > routes, so this value is definitely higher. I'm sure that setting t too > high could result in some memory issues. > > Additionally, you also want to raise net.ipv6.route.gc_thresh to avoid > running the garbage collector too often. I found that the rule of thumb > here is 1/4 the size of ipv6.route.max_size. > > I did find that in Linux kernel 5.2 there is a message output to the > kernel ring buffer when the ipv6.route.max_size is hit, so you at least > have a *clue* what is going on. In 4.19, which is what Debian Buster is, > you don't get that clue. >
In iernel 4.14 we haven't seen the issue. In 5.7 the issue still exists. I can confirm that increasing net.ipv6.route.max_size is a workaround. Regards, Bene -- Karlsruher Institut für Technologie (KIT) Steinbuch Centre for Computing (SCC) Benedikt Neuffer Netze und Telekommunikation (NET) Hermann-von-Helmholtz-Platz 1 Gebäude 442 Raum 122 76344 Eggenstein-Leopoldshafen Telefon: +49 721 608-24502 Fax: +49 721 608-47763 E-Mail: benedikt.neuf...@kit.edu Web: https://www.scc.kit.edu Sitz der Körperschaft: Kaiserstraße 12, 76131 Karlsruhe KIT – Die Forschungsuniversität in der Helmholtz-Gemeinschaft Signaturversion: 19.1.0 beta
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