[Dnsmasq-discuss] What is memory usage per cached dns address

[Urgen Sherpa]

Hello :)
Any idea on memory usage per cached dns address ? Lets say if i have
500,000 cache size(and if cache is full) how much memory is expected to be
used on linux server with spare 160G memory?

Currently when cachesize is set to 50, the ps aux RSS is 2500kB with below
logs

Jul 25 17:41:54 servlp6 dnsmasq[15701]: cache size 50, 52/358 cache
insertions re-used unexpired cache entries.

Jul 25 17:41:54 servlp6 dnsmasq[15701]: queries forwarded 687, queries
answered locally 1

Jul 25 17:41:54 servlp6 dnsmasq[15701]: queries for authoritative zones 0

Jul 25 17:41:54 servlp6 dnsmasq[15701]: server 10.0.3.2#53: queries sent
687, retried or failed 144


***@servlp6:~# ps aux | grep dnsmasq

*dnsmasq* 15701 0.0 0.0 52864 2504 ? S 16:28 0:00
/usr/sbin/*dnsmasq* -x /var/run/*dnsmasq*/*dnsmasq*.pid -u *dnsmasq* -r
/var/run/*dnsmasq*/resolv.conf -7
/etc/*dnsmasq*.d,.dpkg-dist,.dpkg-old,.dpkg-new
--local-service --trust-anchor=.,19036,8,2,49AAC11D7B6F6446702E54A1607371
607A1A41855200FD2CE1CDDE32F24E8FB5


Warm Regards
Sherpa

[Simon Kelley]

A cache entry for one DNS address, on a 64 bit machine, with IPv6
support compiled in, is 100 bytes. A few other datastructures grow in
proportion to the cache size, but not by much. If you assumed 128 bytes
per cache entry that should be pretty close.

That gives memory usage around 62Mb for you 500,000 cache size, which is
pretty trivial on a big server.

Note that, whilst forward cache lookups are efficient to very large
cache sizes, reverse (ie address to name) ones will get slower linearly
with cache size, so check you're not burning CPU and elapsed time on those.

Simon.

Post by Urgen Sherpa
Hello :)
Any idea on memory usage per cached dns address ? Lets say if i have
500,000 cache size(and if cache is full) how much memory is expected to
be used on linux server with spare 160G memory?
Currently when cachesize is set to 50, the ps aux RSS is 2500kB with
below logs
Jul 25 17:41:54 servlp6 dnsmasq[15701]: cache size 50, 52/358 cache
insertions re-used unexpired cache entries.
Jul 25 17:41:54 servlp6 dnsmasq[15701]: queries forwarded 687, queries
answered locally 1
Jul 25 17:41:54 servlp6 dnsmasq[15701]: queries for authoritative zones 0
Jul 25 17:41:54 servlp6 dnsmasq[15701]: server 10.0.3.2#53: queries sent
687, retried or failed 144
*dnsmasq*  15701  0.0  0.0  52864  2504 ?        S    16:28   0:00
/usr/sbin/*dnsmasq*-x /var/run/*dnsmasq*/*dnsmasq*.pid -u *dnsmasq*-r
/var/run/*dnsmasq*/resolv.conf -7
/etc/*dnsmasq*.d,.dpkg-dist,.dpkg-old,.dpkg-new --local-service
--trust-anchor=.,19036,8,2,49AAC11D7B6F6446702E54A1607371607A1A41855200FD2CE1CDDE32F24E8FB5
Warm Regards
Sherpa
_______________________________________________
Dnsmasq-discuss mailing list
http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss