I use ubuntu 11.10, apache2 with varnish, php5-fpm and xcache. I have 512mb ram with 4 cpus. linux kernel version 3.
What are the optimal xcache settings?
Should I make also some changes and settings also at my kernel/system to allow it have more memory size than the default 16?
Some quick comments (I have just been reading a bit about it and tweaking my own set up).
Set xcache.count to the number of CPU cores (eg, if your 4 CPUs are dual-core, then use 8 as the value)
Only worry about cache.var_size if you are using the variable cache (via xcache_get(), etc; check the api doc )
Otherwise, I have xcache.size set to 64M and it's enough. Using the admin/status page you might be able to see that you have too many cache misses (missed hits) and then you could increase xcache.size.
