Scalability of CMSMS

[NickR]

I have done some benchmarks with CMSMS, nothing scientific, using Microsofts Website stress test, just to get an idea of how CMSMS will scale. I used 6 concurrent connections as using 10 connections gave same results on both machines, I guess there is only so much mysql and php can do at once.

If you have plenty of free ram, CPU ( under clocked my CPU and pages a second went down by roughly same proportion) is the limiting factor for the number of pages a second CMSMS can do. Same thing happens with Xaraya as well.

If you have limited RAM, MYSQL database gets strangled and seriously hampers numer of pages a second, this is not a CMSMS thing, as I tried Xaraya on our live server, which has very little ram without caching and both CMSMS and Xaraya would serve about the same number of pages a second, where as on my home server with 1 gig of ram CMSMS was twice as quick as Xaraya.

To confirm this, I tested Xarayas output cache, which can cache to disc or database, caching to mysql doubled the  page output of our test server (as less queries being fired), but caching to disc saw things go about ten times as fast than with no caching in Xaraya.

Back on my home server Xaraya with output cache to database sped up to be slightly faster than CMSMS, but change to Xarayas disc output cache and the pages a second doubled over CMSMS - I assume that is because there is less CPU load in having to generate the content everytime (there is still a bit of background code still running for stats, hitcount and permissions still running in Xaraya).
Clocking my CPU back (from 800mhz to 700mhz) and Xarayas caching dropped by a little amount (10% for both types).

Xaraya also is very memory effecient (has a 100% lazyloading 1 file per function) compared to my fully loaded CMSMS (6.5 megs vs 10 megs uncached for me) - on limited ram, does'nt make any noticable peformance as mysql is starved of ram and is the significant bottleneck.

Dunno how this will help, but thought it would be useful information to someone, shows that php is CPU dependant and MySQL is ram dependant and output caching to disc will help cpu and mysql load.