[Pdns-users] PowerDNS cannot handle the load?

[Stephane Bortzmeyer]

On Wed, Apr 09, 2003 at 02:04:08PM -0700,
 Mike Benoit <mikeb at netnation.com> wrote 
 a message of 72 lines which said:

> If your not updating records often, I recommend bumping these waaay up.
> We use:
> 
> cache-ttl=3600
> query-cache-ttl=86400
> negquery-cache-ttl=86400

I tried that and it improves performance... once the data is in the
cache. Initial performance at startup is still very low.

> Something is definately wrong if you can only do ~200queries/sec with
> this hardware. If I recall correctly, Bert was seeing in excess of
> 10,000 queries/sec with a TDB backend on similar hardware. 
...
> Unfortunately PostgreSQL comes configured out of the box for
> portability/stability in mind, therefore it requires quite a bit of
> tuning to get the performance up to par. 

I tried with only the BIND backend, to avoid any PostgreSQL
issues. After starting up PowerDNS, I perform several tests with the
same request file:

  Queries per second:   138.338800 qps
  Queries per second:   172.432285 qps
  Queries per second:   847.873270 qps
  Queries per second:   2054.151543 qps
  Queries per second:   2091.337055 qps

So, when the cache fills up, things are better. It seems that
transferring from the backend to the cache is very slow but, once it
is in the cache, it is better.

Still, it is not something reasonable to me. 

nsd and BIND9 are very consistent: the performance is the same from
one run to the other.

Here is "top" output when queryperf runs:

top - 13:43:41 up 41 min,  2 users,  load average: 15.22, 9.36, 5.65
Tasks:  90 total,  18 running,  72 sleeping,   0 stopped,   0 zombie
Cpu(s):  91.4% user,   8.6% system,   0.0% nice,   0.0% idle
Mem:    904948k total,   398812k used,   506136k free,    37712k buffers
Swap:   979956k total,        0k used,   979956k free,   253492k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  Command           
  959 root      20   0 58404  57m 1588 R 29.2  6.5   1:50.91 pdns_server       
  960 root      20   0 58404  57m 1588 R 28.5  6.5   1:47.37 pdns_server       
  958 root      17   0 58404  57m 1588 R 28.2  6.5   1:06.91 pdns_server       
  953 root      15   0 58404  57m 1588 R 27.9  6.5   1:54.51 pdns_server       
  963 root      19   0 58404  57m 1588 R 27.5  6.5   1:48.55 pdns_server       
  964 root      20   0 58404  57m 1588 R 27.5  6.5   1:13.82 pdns_server       
  948 root      17   0 58404  57m 1588 R 27.2  6.5   1:52.94 pdns_server       
  951 root      16   0 58404  57m 1588 R 26.9  6.5   1:51.23 pdns_server       
  962 root      20   0 58404  57m 1588 R 25.6  6.5   1:05.66 pdns_server       
  952 root      15   0 58404  57m 1588 R 25.2  6.5   1:12.25 pdns_server       
  961 root      16   0 58404  57m 1588 R 24.9  6.5   1:50.97 pdns_server       
  965 root      14   0 58404  57m 1588 R 24.9  6.5   1:38.58 pdns_server       
  966 root      14   0 58404  57m 1588 R 23.9  6.5   1:26.38 pdns_server       
  967 root      14   0 58404  57m 1588 R 18.4  6.5   1:36.65 pdns_server       
  369 ntop      11   0  7928 6080 1372 S  4.6  0.7   1:13.14 ntop