Deadwood at OpenWRT

[Sebastian Müller]

Am 10.09.2010 10:28, schrieb Sam Trenholme:
>>> I’m very curious how well Deadwood works on an embedded OpenWRT host.
>>>
>> I just used the host.txt Juergen Daubert posted a few days ago and ran
>> it from a client. I am connected on a cable connection with a latency of
>> 10ms to my upstream DNS Server.
>>
>> It took 0m57.597s to finish, before the MaraDNS upstream server cached
>> the results and 0m13.621s after the upstream MaraDNS cached it.
> 
> Nice, and very fast.  Is Deadwood able to do its own recursion with
> reasonable performance on an embedded OpenWRT host?  I know that, on
> Windows, Deadwood needs three or four megs of memory to work as a
> fully recursive nameserver with 1024 entries in the cache; I’m
> thinking that Deadwood would use quite a bit of the processing power
> and memory of a WRT54G (8 megs of ram, 2 megs of flash); it may be
> necessary to reduce the cache size to 512 entries to stop Deadwood
> from hogging all of the memory (quick test: Deadwood uses 2.2 megs of
> memory with a 512-entry cache in Windows).  It’s a good thing
> Deadwood’s LRU cache design helps Deadwood run well when there are
> more entries being processed than what will fit in the cache.
> 

I did the test 3 times without using an upstream server. It took
real    2m40.678s
real    2m17.158s
real    2m16.010s
(I didn't change the order)

Deadwood uses 5% of memory, my router got 32mb overall / displayed 29mb
in top.
(29mb|32mb) * 0.05 = 1.45mb|1.6mb

#free
            total         used         free       shared      buffers
Mem:        29484        20736         8748            0         1100


during the test, top displayed, a CPU usage of 1-3%. But my router got a
fast 400Mhz CPU and DDR2.

I got an old Linksys WRT54GS running OpenWRT, too. It got a 200MHz CPU
which wasn't able to handle QoS on a 25mbit line (CPU overloaded at
14mbit). I will revive it later and test Deadwood performance on it.


>> I didn't ran into any trouble yet, using Deadwood since a few weeks
>> (2.9.03) on my TP-Link TL-WR1043ND. One time I got a segfault, but after
>> recompiling (and changing nothing) everything worked. It is possible
>> that I forgot to shutdown DNSMasq which is the default resolver on
>> OpenWRT before running Deadwood.
> 
> Hmmm...maybe.  I’ll blame it on cosmic rays unless we find a way to
> consistently reproduce it.
>

Cosmic is a good reason for now. If it happens again I will search a
better reason.

>> Yes, there is a strip tool, after striping the file sizes 100768 bytes.
>> I used -s for striping
> 
> That’s bigger than I thought it would be.  It’s amazing how compact
> the x86 instruction set is; my guess was that the overhead for RISC is
> making a binary 50% bigger but it’s closer to 55% bigger.  I wonder
> how large the AMD thumb ISA binary would be?  (OK, time to install an
> ARM cross-compiler to find out...)
> 
>> I mainly posted here to
>> reach people who are interested in getting Deadwood running off x86.
> 
> I’m very interested in that target also.  Deadwood is about as small
> as a full-featured recursive DNS server can get, and I think it makes
> as much sense to put it in an embedded router as on a desktop PC.