[httperf] time wait limits
david at lang.hm
david at lang.hm
Mon Aug 11 01:51:15 PDT 2008
I spent a bit of time fighting httperf over the weekend, and from reading
the list archives there's a lot of problems in figuring out how to trigger
parallel requests during testing.
my test environment
server Debian Etch running apache 2
32G ram, 4x dual core Opteron CPU's, hardware raid controller with battery
backed cache and 2x 144G 15K rpm drives
client same
using the apache benchmark tool (ab) I could get 21,000 connections/sec
with apache prefork, and 23,000 connections/sec with apache worker
with httperf I had trouble getting anywhere near those numbers.
to deal with the problem of running out of client ports I set
net.ipv4.ip_tw_reuse=1 and net.ipv4.ip_tw_recycle=1
this lets me get up to several thousand connections/sec
by setting the --rate to several thousand and the --num-calls to 20 or so
I was able to get it to start doing more connections in parallel
the problem I keep running into is the file descripter limits. why is it
that the max file descripters are capped at FD_SETSIZE no matter what the
ulimit is set to?
it would be handy if the option were to be added to be able to specify the
source IP address to use (or to be able to provide a list/range of
addresses to use)
with modern hardware it's really easy to exceed the limits
David Lang
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