"Thomas Rosenstein" <[email protected]> writes:
> On 6 Nov 2020, at 12:18, Jesper Dangaard Brouer wrote: > >> On Fri, 06 Nov 2020 10:18:10 +0100 >> "Thomas Rosenstein" <[email protected]> wrote: >> >>>>> I just tested 5.9.4 seems to also fix it partly, I have long >>>>> stretches where it looks good, and then some increases again. (3.10 >>>>> Stock has them too, but not so high, rather 1-3 ms) >>>>> >> >> That you have long stretches where latency looks good is interesting >> information. My theory is that your system have a periodic userspace >> process that does a kernel syscall that takes too long, blocking >> network card from processing packets. (Note it can also be a kernel >> thread). > > The weird part is, I first only updated router-02 and pinged to > router-04 (out of traffic flow), there I noticed these long stretches of > ok ping. > > When I updated also router-03 and router-04, the old behaviour kind of > was back, this confused me. > > Could this be related to netlink? I have gobgpd running on these > routers, which injects routes via netlink. > But the churn rate during the tests is very minimal, maybe 30 - 40 > routes every second. > > Otherwise we got: salt-minion, collectd, node_exporter, sshd collectd may be polling the interface stats; try turning that off? >> >> Another theory is the NIC HW does strange things, but it is not very >> likely. E.g. delaying the packets before generating the IRQ >> interrupt, >> which hide it from my IRQ-to-softirq latency tool. >> >> A question: What traffic control qdisc are you using on your system? > > kernel 4+ uses pfifo, but there's no dropped packets > I have also tested with fq_codel, same behaviour and also no weirdness > in the packets queue itself > > kernel 3.10 uses mq, and for the vlan interfaces noqueue Do you mean that you only have a single pfifo qdisc on kernel 4+? Why is it not using mq? Was there anything in the ethtool stats? -Toke _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
