[Dnsmasq-discuss] dnsmasq using 100% of cpu

Donald Sharp donaldsharp72 at gmail.com
Mon Feb 17 13:31:13 GMT 2020


Running:

sharpd at eva:~/dnsmasq$ /sbin/dnsmasq --version
Dnsmasq version 2.80  Copyright (c) 2000-2018 Simon Kelley
Compile time options: IPv6 GNU-getopt DBus i18n IDN DHCP DHCPv6 no-Lua TFTP
conntrack ipset auth DNSSEC loop-detect inotify dumpfile
----

When I install several hundred thousand routes into the kernel and
remove them( or some variation thereof ), dnsmasq eventually ends up
running 100% cpu:

top - 18:45:18 up 1 day,  7:44,  1 user,  load average: 2.70, 2.65, 2.34
Tasks: 424 total,   3 running, 421 sleeping,   0 stopped,   0 zombie
%Cpu(s): 12.1 us,  6.9 sy,  0.0 ni, 80.2 id,  0.0 wa,  0.0 hi,  0.7 si,
 0.0 st
MiB Mem :  32131.3 total,  19483.6 free,   6620.3 used,   6027.4 buff/cache
MiB Swap:  32718.0 total,  31693.0 free,   1025.0 used.  24698.2 avail Mem

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+
COMMAND
 293183 nobody    20   0   11040   2040   1688 R  99.7   0.0 148:48.40
dnsmasq

strace output:

poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=POLLERR}])
poll([{fd=3, events=POLLIN}, {fd=4, events=POLLIN}, {fd=5, events=POLLIN},
{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=8, events=POLLIN}], 6,
-1) = 1 ([{fd=4, revents=PO^Cstrace: Process 293183 detached

I can pretty much make this happen at will.  What can I provide to help
debug this?

As a side note, I was not placing these routes into the default linux
routing table.  Does dnsmasq need to be paying attention to these routes?

donald
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/attachments/20200217/93f06b1a/attachment.html>


More information about the Dnsmasq-discuss mailing list