We have a license manager server that runs on a single host. It accepts TCP connections, performs some sort of exchange (I haven’t reverse-engineered it), and keeps the TCP connection open for the duration that the client is authorized to run the program. We have purchased a large number (>500) licenses. So this server has hundreds of open TCP connections.

We have an uncooperative vendor who will not provide access to the source code of their license server and will not provide us with help in tuning the Unix server.

I would like to tune the server so that it can respond to hundreds of connections coming in within a few miliseconds. We do not have source-code to the server, but we can tune the Linux OS that it is running on.

My questions: what parameters should we tune?

I’ve already modified the client to do random back-off and retry if it can’t connect to the server.

closed as too broad by joeqwerty, Wesley, kasperd, womble Jul 23 '18 at 2:34

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • I have in the past deployed software which would handle that number of connections on a cheap VPS running Ubuntu Server with no tuning whatsoever. So until you have actually identified a problem there is no question to be answered here. Also if there was a set of parameters guaranteed to give good performance in every setting you could expect those to have been made the default already. – kasperd Jul 22 '18 at 12:49
  • Well, this is a real-world problem, and the vendor will not provide us with access to the source code. – vy32 Jul 22 '18 at 17:54

Providung a laundry list of tunable parameters here will do little to put your server into a better state. Performance tuning is a process, not a task. Measure, tweak, and measure again. Restrict your tuning to one param at a time to isolate impact. Brendan Gregg is one smart dude when it comes to performance tuning (he wrote the book) so check his page out on the subject... http://www.brendangregg.com/linuxperf.html

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