How many simultanious users

Lazy lazy404 at
Thu Jul 16 12:28:38 CEST 2009

>>> assuming that each user loads 40 files in 1 minute we get
>>> 12000*60/40=18 000 users per minute
>>> Is it possible to get half of that 18k users/per minute in real word
>>> ignoring the amounts of traffic it will generate ?
>> I'd say so, but it depends on how big the data set is. If you can store it
>> in memory, varnish is ridiculously fast. I also wouldn't recommend relying
> i think it will fit in to ram, i will be a single site
>> on a single Varnish for more than a few thousand requests per second. If
>> something goes wrong (suddenly getting lots of misses for instance), it
>> will quickly spread.
>> For comparison, I'm looking at a box with roughly 0.4 load serving
>> 2000req/s as we speak, and that's on 2xDual Core Opteron 2212. Going by
>> those numbers, it should theoretically be able to handle almost ten times
>> as many requests if Varnish scaled as a straight line.
>> That'd give you roughly 18000 req/s at peak (give or take a little...) Now
>> you're talking about 8 cores, that should be 36k req/s. That's _not_
>> unrealistic, from what we've seen in synthetic tests. If each client
>> requires 40 items, that means roughly 900 clients _per second_. Or 54k in a
>> minute. This math is all rough estimates, but the foundation is production
>> sites and real traffic patterns.
>> The problem is that getting your Varnish to deal with 36k req/s is rather
>> difficult, and you quickly run into network issues and similar. And at 36k
>> req/s you can hardly take any amount of backend traffic or delays before it
>> all falls over.

today i did some ad-hoc tests with 45 byte body,

when I enable keep-alive I'm getting 39k req/s with 100 concurrent
gets and over 40k with 300 concurrent connections (max cpu load was
under 2 cores for varnish)

without keep alive i'm stuck with 12k req/s, that might be end of ab's
performance in making new connections or
kernel, i tried the performance tips from the wiki, but id didn't make
a significant difference in this test,
Later i will try to use a benchmark running on another machine.

12k req/s is more then enough for me already so I'm happy with that

Michal Grzedzicki

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