[Pdns-users] Performance issues

[Martijn Reening]

Hello Bert,

We are running PowerDNS 4.1.3 and have tested against MySQL 5.1.73 en
PostgreSQL 10.4. It runs on CentOS 6.9, tested with both kernel versions
`2.6.32-696.20.1.el6.x86_64` and `4.15.13-x86_64-linode106`.

Running bench-db for all domains reports:

   1.32192 millisecond/lookup
   Retrieved 31554 records, did 10000 queries which should have no match
   Packet cache reports: 0 hits (should be 0) and 0 misses

In the output of dnsgram are many lines like this, especially during the
performance drops:

   2018-07-05 16:12:12: Auth server dropped too many questions (683 vs
151), diff: 532

I could put the output files somewhere online if needed.

dnsscope produces the following output:

   PCAP contained 948599 correct packets, 10 runts, 0 oversize, 0 non-UDP.
   Timespan: 0.310556 hours
   0 non-DNS UDP, 0 dns decoding errors, 2 bogus packets
   Ignored fragment packets: 0
   Dropped DNS packets based on recursion-desired filter: 0
   DNS IPv4: 761357 packets, IPv6: 187242 packets
   Questions: 518087, answers: 430510
   492392 (95.04% of all) queries did not request recursion
   21131 answers had recursion desired bit set, but recursion
available=0 (for 92 remotes)
   87277 queries went unanswered, of which 128 were answered on exact
retransmit
   71 responses could not be matched to questions
   439883 questions requested EDNS processing, do=1: 412804, ad=1: 9,
cd=1: 319760
   Rcode                    Count
   No Error                 318934    (74.1%)
   Server Failure           422       (0.1%)
   Non-Existent domain      14897     (3.5%)
   Query Refused            96257     (22.4%)
   0.19% of questions answered within 50 usec (0.19%)
   23.38% of questions answered within 100 usec (23.19%)
   42.11% of questions answered within 200 usec (18.73%)
   48.09% of questions answered within 300 usec (5.98%)
   51.58% of questions answered within 400 usec (3.49%)
   57.36% of questions answered within 800 usec (5.78%)
   59.76% of questions answered within 1000 usec (2.41%)
   70.02% of questions answered within 2.00 msec (10.26%)
   85.34% of questions answered within 4.00 msec (15.31%)
   95.91% of questions answered within 8.00 msec (10.57%)
   99.43% of questions answered within 32.00 msec (3.52%)
   99.52% of questions answered within 64.00 msec (0.09%)
   99.65% of questions answered within 256.00 msec (0.12%)
   99.86% of questions answered within 1024.00 msec (0.21%)
   127 responses (0.03%) older than 2 seconds
   Average non-late response time: 4702.69 usec
   Saw questions from 29140 distinct remotes, answers to 1
   Saw 29139 unique remotes asking questions, but not getting RA answers

On 24/07/2018 13:58, bert hubert wrote:
> On Tue, Jul 24, 2018 at 01:54:53PM +0200, Martijn Reening wrote:
>> We have run out of ideas where to look and what to tune. Perhaps anyone
>> here could help us further?
> 
> could you tell us what database you run, what version of PowerDNS, what the
> output is of 'pdnsutil bench-db', what operating system? Thanks.
> 
> Also, can you start running a tcpdump and feeding it through dnsscope and
> dnsgram?
> 
> Also some sample domain names we can query would be nice, maybe we can see a
> pattern.
> 
> Thanks.
> 
> 
> 	Bert
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> Pdns-users mailing list
> Pdns-users at mailman.powerdns.com
> https://mailman.powerdns.com/mailman/listinfo/pdns-users
> 

-- 
Regards,

Martijn Reening