[squid-users] Max throughput of CARP Proxy

Hi folks,

I'm testing a CARP setup and try to find out what the maximum throughput
is. After a lot of testing I'm stuck with 5000 req/s and ca. 220 mbit/s
in and out. Whatever I do I can't make it faster. Does anyone have an
idea whats going on or if I do something wrong? How can I find out what
the bottleneck is?

This is the test setup:

- 1 GBit NICs and even faster switches, all servers in the same subnet
- 1 CARP and 5-9 Proxies as parents
- all proxies use AUFS and cache_mem
- proxies are warmed up, meaning I ran the test multiple tests so that
all content is on the proxies and they don't have to get anything from
the original servers
- the CARP does not cache anything(cache_mem 0 MB & cache_dir null no-store)
- used Version: Squid 2.7.STABLE7-2
- Kernel is the standard Etch 2.6.18

The test itself:
I use http_load[1] and start it on four servers at the same time with 50
parallel requests. It uses a list with appr. 3 mio. URLs with most of
the files being smaller than 4 kB but bigger than 2 kB. The test runs 30
minutes.

The CARP uses appr. 25% CPU and has lots of free memory. I get no
problems reported in cache.log or syslog. And the throughput of 5k req/s
and 220 mbit/s doesn't change with five, seven or nine parent proxies.

[1] http://www.acme.com/software/http_load/http_load-12mar2006.tar.gz

Any ideas and hints are welcome.

Cheers, Markus
Received on Thu Feb 04 2010 - 10:07:02 MST