100% CPU load with device scanning enabled

[Kees Meijs]

Update:

strace(1) shows the following in regard to Open vSwitch in an endless loop:

> socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 40
> ioctl(40, SIOCGIFNAME, {ifr_index=6, ifr_name="vlan1105"}) = 0
> close(40)                               = 0

This doesn't make any sense (at least, to me) since the interface
vlan1105 isn't related to any bridge configuration at all. Only outbound
routes (originating from BGP) point to an address via interface
vlan1105. As the name implies this is just a VLAN on a direct physical
network port.

And BIRD (2.0.4-1):

> poll([{fd=4, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8,
> events=POLLIN}, {fd=9, events=POLLIN}], 4, 3000) = 1 ([{fd=7,
> revents=POLLIN}])
> recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0,
> nl_groups=0x000040}, msg_namelen=12, msg_iov=[{iov_base=[{{len=68,
> type=0x19 /* NLMSG_??? */, flags=0, seq=806042, pid=2639368684},
> "\2\26\0\0\376\f\0\1\0\0\0\0\10\0\17\0\376\0\0\0\10\0\1\0X\335d\0\10\0\6\0"...},
> {{len=0, type=0 /* NLMSG_??? */, flags=0, seq=0, pid=0}}],
> iov_len=8192}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 68

There's just a little of polling going on but it seems as every poll
results in the socket being opened by ovs-vswitchd, for each route
present. And again, and again.

Regards,
Kees

On 06-05-19 20:22, Kees Meijs wrote:
> Sorry: shouldn't happen.
>
> Meanwhile we tested BIRD 2.0.4 as well (compiled from source) with the
> same result. The process ovs-vswitchd completely consumes a CPU thread.
>
> When disabling the exportation of the routes (full feed, so 700k+
> routes) the load drops back to nothing.