9.2.5 db causes high cpu? was: Re: BIND 9.2.5rc1 is now available.

Stefan Schmidt zaphodb--bind at zaphods.net
Thu Feb 17 17:26:28 UTC 2005

I should also say something on memory usage.
The following are identical machines with roughly the same uptime, same kernel
etc. and situated behind an IPVS loadbalancer giving the both of them nearly
the same query rate. (It just differs around 20-30 queries/s where the bind9
instance seems to be preferred which is odd for it seems to have the higher
delay for answering already cached contents.)

2x bind 8.4.6-REL:
 5128 bind      16   0  307m 302m 1104 S 15.3 29.9   2785:50 named              
 5126 bind      15   0  299m 294m 1104 S 12.6 29.1   2681:28 named              
(ps auxw)
bind      5126  8.8 29.1 306456 301600 ?       Ss   Jan27 2681:38
/usr/sbin/named -4 -t /var/named -u bind -c /etc/namedb/named.conf.1
bind      5128  9.1 29.8 314696 309700 ?       Ss   Jan27 2786:00
/usr/sbin/named -4 -t /var/named -u bind -c /etc/namedb/named.conf.2

1x bind 9.2.5beta2:
 3918 bind      21   0  623m 588m 1700 S 66.5 58.1   4109:35 named              
(ps auxw)
bind      3918 57.4 58.1 638060 602356 ?       Ssl  Feb12 4109:48
/usr/sbin/named -t /var/named -u bind -n 2

max-cache-size 700M;
recursive-clients 2000;
tcp-clients 300;
and some acls. (two bogon lists)

/proc/<pid>/status shows the VmRSS of the bind9 process to be stable in the
short term.

Our postmaster has a problem that maybe related: He is running a bind9
authorative-only server on a 1GB RAM machine and is serving some really big
DNSRBL zones for use by two recursive nameservers and a few external clients.
On startup he told me the named process uses around 800MB of memory but it
seems to grow on that in a non-deterministic fashion up to the point where
the system keeps on swapping. The first time he figured it needed one to two
weeks to grow to that extent but the second time he said it was just within
one or two days. Is there any way to reduce the memory footprint of a bind9
memory only server? 

"And how would we hide a 30,000-ton submarine?"
"You hide a submarine by sinking it," Painter said angrily.
"They're designed to do that, you know."
- Ryan and Adm. Painter, "The Hunt for Red October" (Tom Clancy)

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