Performance Issues

[mike]

new install, websites take more than twice as long to load

[mike]

Ive setup a new cPanel vps to migrate a couple troubled websites for a customer. Ive installed the trial of cloudlinux and have tested that I can take down just a single site while the rest of the sites on the server are fine. The problem though is when comparing load times between the original server and the new server, pages take more than twice as long to load. one example is a magento site (no comment) that takes 686ms on the original server and 1.64s on the cloudlinux server. if I disable the hostinglimits mod in apache the site then loads in 682ms on the cloudlinux server. But that kinda defeats the whole purpose of going to cloudlinux.

[iseletsk]

Mike,

How many cores does your VPS has?
If it has just one core, try increasing CPU limit to 50% of 75%
If it has 2 cores -- try increasing it to 50%

The thing is that by default you have 25% of total CPUs, and on 2 core servers, it means have a core at any given time -- or it means that most applications that are cpu bound, will run twice as fast as before. Hence the timing increase.

[mike]

The VPS has 4 cores. I had tried changing the cpu limit to 30%, 50% and 80% but it had no effect. The way I was able to tell was watching lvetop when running a stress test from my workstation. When the cpu was set to 25%, I could see it max out at 25%, I could lower it, but it never took anything higher than 25%. I tried setting the individual ID, even setting the cores to 2 and 4 for lve. This was after the initial install of cloudlinux and re-run of easyapache. I have since added a few modules and re-ran easyapache a few times, but never re-tested the cpu settings.

I removed the individual id settings from the config and now have default lve settings to 50% cpu and 1 core. I was able to stress the site out at 50%. I tested the load times again and they are now very close, ms apart (this is with the CL server using SuPHP and the non-CL using DSO) . Its nice seeing the server still responsive while stressing out a site.

Thanks.

[iseletsk]

1. DSO will be much faster then suPHP either way. You can use DSO with CloudLinux, and it will still limit everything. Try switching to DSO on CL server, and see if the performance will be the same

2. The reason you cannot go above 25%, is because you have 4 cores, and ncpu=1, this means that any time you can use no more then 1/4 (25%) of CPU resources. Try setting ncpu=2 and CPU=25. If you are running latest kernel (lve0.8.44), you can do it by running: lvectl set default --ncpu=2 --save --force
And then lvectl apply all
If you are running older version of kernel, you will need to reboot (or same command can cause server crash). Upgrade kernel, and then change ncpu.