Running on 4 cores can upgrade to 8 if required (sponsored). VBSeo seems to like to eat resources also.
Shouldn't.
Had a vb3 with seo and such with few million posts/thousands users, mostly like 100-500 online tops I'd say, but guests would get the users in the thousands. PHP was normally around 6%-18% roughly.
I'd not touch eaccelerator with a 10 foot pole, enable xcache in vb config might help (vb approves of xcache) I think we tried memcached, it sometimes adds a few 100ms overhead like MySQL over lan adds 100-150 or so normally. The longer php takes to execute, the more cputime used, the less you'll beable to push.
I've worked with php content for over 5 years in high demand envs...
You may also want to run LSPHP as child and such
Since the admin panel was handy try XCache, enable it in config, maybe disable MySQL persistent, disable suexec, add realpath cache larger in php.ini, and try this php config in lsws admin panel.
I do help people free, mostly in IRC's but since I happen to be in the lsws admin panel this may be of use, I've modified it slightly to your needs though we run something similar in a high demand shared enviorment with maybe 1 minute downtime a month while pushing a few million requests a day mostly php, so you may find it works nice compared to now settings. Also take the no suexec in consideration to XCache functions 100%
It's in external app -> lsphp5 -> Environment
Code:
PHP_LSAPI_MAX_REQUESTS=2000
PHP_LSAPI_CHILDREN=65
LSAPI_ACCEPT_NOTIFY=1
LSAPI_AVOID_FORK=1
LSAPI_CHILDREN=0
LSAPI_MAX_REQS=2000
LSAPI_EXTRA_CHILDREN=25
If you have memory leaks in PHP make sure to lower max requests on both lines, if you can get PHP down to roughly 10%, slowly raise lsapi_children till cpu's all being used good.
So with 400% total, you prob got mysql untuned and what not doing 100-150%, so factor in the cpu your php is using and thats how many children you can push without overloading, maybe set backlog to 100-150 in that same page.
Give XCache about 32mb to 16mb shm. Since so many processes spawned it's sorta useless to give it too much, it's quick on the fly. Also look into giving php/mysql /dev/shm for tmp's if you can afford the ram. If your disks are bottlenecked and mysql bottlenecked, theres your issue php wont run right.
Almost every site we pump executes in under .02 seconds and delivers in 100ms-500ms on avg depending on your latency of course but in general around that low, if your vb's executing like .1 and delivering around 800-1s+ you def got tuning issues and what not.
I've found vB3 to use very little resources, sometimes .6-2% cpu with that 1000+ user site and more. Sadly the vb and other forum's benchmarks I'm looking to do is in the future not already done or I'd show you that these scripts can run so low utilization.
LSPHP doesn't run multiple requests per process so doing like 65% and what not is just totally eating your shit up, hell strace the php process old trick, sometimes you'll find it just looking for directories or finding missing files. pro hint, the realpath cache and high php req's helps that, we use 1000 for our shared to avoid random client's having a memory leak, then again 12gb ram and the ability to add more cores on the go helps with our setup.
Good luck
