On 16/10/2013 1:32 μμ, Nikolaos Milas wrote:

Now my problem is that there seems to be a limit of performance...

Increasing stress load more than that (I am using tsung for load testing), results only to increasing "error_connect_emfile" errors.

I have been trying to resolve this behavior and I increased file descriptors to 400.000:

   # ulimit -n
   400000

since:

   # cat /proc/sys/fs/file-max
   592940

Now, I am running the following test: X number of users per sec visit the homepage and each one of them refreshes the page 4 times (at random intervals).

Although the test scales OK until 500 users per sec, then "error_connect_emfile" errors start again and performance deteriorates. See the attached comparative chart.

So, I have two questions:

1. Is there a way we can tweak settings to make the web server scale
   gracefully up to the limit of its resources (and not deteriorate
   performance) as load increases? Can we leverage additional RAM (the
   box always uses up to 3.5 GB RAM, despite the load, and despite the
   fact that the VM now has 6 GB)?
2. If not, how can we safeguard the web server by setting a suitable
   limit which cannot be surpassed to cause performance deterioration?

Please advise.

Thanks and regards,
Nick

<<attachment: compare.png>>

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