Siege Load-testing

Siege command line:

siege -f links.csv -c 150 -t15m -d 7 -iv -m "Company1 Mar 31 2020" -l

-c - concurrent users
-t15m - test time
-d 7 - 7sec delay for each user
-i - INTERNET user simulation, hits URLs randomly
-m - MARK, mark the log file with a string
-l - log file, if it isn't specified, then default is used: /var/siege.log

I'm increasing concurrent users number with step 50 within each test.

Tips&tricks:

I got unexpected good results with higher concurrent users number after previous bad with lower ones.
The reason were FPC cache (redis in my case) and OpCache.
So, tricks are cleaning FPC and OpCache caches before each test.
In my case,
redis-cli -p 6380 FLUSHALL 
and restarting php