[Olsr-dev] olsrd-tip burns cpu,..

Markus Kittenberger (spam-protected)
Wed Dec 10 10:29:43 CET 2008

Today(Yesterday) i found olsrd consuming "all" the cpu for about 10 hours

so i investigated,..

after restarting oslr everything is was fine until i fired up a interface
(which has been down at oslr start)
or if start olsr on a non empty routing table (routes from a previous olsr
crash, or kill), and same will happen within 1-2 minutes, without any ifup
or down (neither by me nor by anyone/thing else)

i tried travelling back the changes of the last days, but couldn`t track
down when it started for long, as older version segfault on my ifup
testcase, and newer versions burn the cpu,..
later i found out that starting olsrd on a filled table causes the same,..
(cpu burning, and crashing of older version)

when loggin olsrd -d 9 the last entries always happen while inserting
removing kernel routes

i have also core dumpes of an still running and cpu burning olsrd (of
http://gredler.at/hg/olsrd/rev/70f18097ab12 which seem s the "oldest" burn
affected version)
and its easy reproduceable on devVserver,.. (maybe everywhere i haven`t
tried somewhere else ...)

but i dont`think the problem was invented in this version, as under same
setup i assume a bit older version will just crash very soon when they start



and heres my list of tested versions, and soem of my notes regardign the
problems i found

-nofork fails, testing wihtout gdb, crashes after ifup, burns cpu on
devVserver (without interfaces all interfaces always up)
various config options fail, no further testing
burns cpu, after ifup, burns when started with an down interface, burns on
devVsrv (prefilled table?)
http://gredler.at/hg/olsrd/rev/70f18097ab12  (34 b)
burns after ifup, burns anyway on devVsrv? (within 2-3 minutes with
prefilled table) (quite stable without)
http://gredler.at/hg/olsrd/rev/ea80a11d61ef (35 replace)
doesn`t compile,..
http://gredler.at/hg/olsrd/rev/d9c2226cb81a (36)
segfaults usually on a single ifudown, 10min stable on stable interfaces and
emtpy table,..
http://gredler.at/hg/olsrd/file/71c35e16799d (37)
50 % ok, 50 % segfaults on single ifup or down, sometimes crashes without
50 % ok, 50 % segfaults on a single ifdown, crashes without reason,.. (or on
a prefilled kernel table)

anyway i commited my last patch,

unfortunately i can`t really test it properly, as olsrd-tip fails the most
suitable testcase for this pach (handling an ifdown (and an ifup) properly)
in all versions i mentioned in this mail
but at least i tested whether it removes the links of an interface, and not
all links of interfaces with same ip adresses,
but if you ifup this interface again olsrd starts to burn a hole into ...,
like the versions before,..


p.s. (written in the middle of testing without any clue what affects the
problems) (-;

for the moment i consider the tip quite and 0.5.6x unuseable for routers
(like most of mine) having not only "always up" interfaces,.. )-;
so my real goal, tracking down the reasons for inconsistent kernel and olsr
routing tables, has too wait until olsr is more stable while running on
dynamic interfaces, which me and funkfeuer need anyway (ok we could change
our needs, but i prefer changin olsrd (-;), and serve as a good starting
testcase for above goal,..

i will continue investigating, and testing, this an related issues, but hmm
.. i could imagine a better start into olsrd for me,.. (-;

anyhow i have to compliment henning and hannes, for their patches and
support during the last days, but hmm i guess there`s a lot more to do (-;

ok i better stop whining now!  (-;  ;-)
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