Quick performance deterioration when No. of clients increases
nmilas at noa.gr
Wed Oct 16 16:07:29 UTC 2013
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
# cat /proc/sys/fs/file-max
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
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?
Thanks and regards,
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