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CPU vs. Load?

Discussion in 'Server Configuration and Hosting' started by Anthony Parsons, Jun 26, 2012.

  1. Anthony Parsons

    Anthony Parsons Well-Known Member

    My server is running a dedicated single processor right now, being a hybrid system. I have plenty of RAM and plenty of HDD RAID10.

    I want to ask independent techs before going to my host requesting an upgrade.

    My site has been progressively growing and thus the load is starting to get towards the 1.0 range as a constant. The CPU has averaged out around 75%, however; when WHM does its update, as it always has done in the past, it is now starting to create I/O that is crippling the server for a brief period whilst the cron runs.

    The cron is fine, the techs have checked it and everything is ok, no corrupt nodes or cron jobs, etc.

    So... is running a CPU close to its maximum reason that the load would be even higher, thus causing the server to create I/O points when running large base software cron jobs?

    Do I simply need to add an additional CPU which would fix the issue? The server has been highly optimised to make it this far... being, as the CPU usage has risen the techs have squeezed more out of areas, streamlining them as needed.

    24hrs - You can see where WHM cron is running... which is actually early morning US time

    Screen Shot 2012-06-26 at 6.54.26 PM.png

    Zoomed IN

    Screen Shot 2012-06-26 at 6.50.29 PM.png
     
  2. CyclingTribe

    CyclingTribe Well-Known Member

    Can the update cron job be broken down into smaller jobs and spanned over a longer time period to flatten the load?
     
  3. Walter

    Walter Well-Known Member

    For me an upgrade makes sense - I don't like running systems at 95% without any buffer.
     
  4. Deebs

    Deebs Well-Known Member

    Anthony,

    Can you find out the wait state for the processor? vmstat or top will show this. If the wait% is high then the CPU is waiting for I/O to complete and adding more CPUs will not fix this.
     
  5. Ghan_04

    Ghan_04 Active Member

    Those look like WiredTree graphs. Assuming they are, you should have access to multiple CPU cores if you are on a hybrid VPS plan. The plan only says one CPU core, but that means that you can have an entire CPU dedicated to you even if other people on the box are using as much CPU as possible. When there is still free CPU usage, you can use more than a single core.

    That being said, I would tend to think that adding another CPU core would NOT fix the issue. The I/O usage you're seeing is, as mentioned by the above poster, the CPU waiting on the disk to finish its task. In short: disk speeds are too slow to keep up. Is there any way you can spread this cron job out over time so that not everything is trying to be done at once?
     
  6. Luke F

    Luke F Well-Known Member

    Look into veryniced, absolute miracle worker in my case for balancing high load websites and very cpu intensive cron tasks with realtime stuff like gameservers all on the same box
     
  7. Anthony Parsons

    Anthony Parsons Well-Known Member

    Yes, the disk read/write can be seen here with the peaks... is that the problem?

    Screen Shot 2012-06-27 at 4.31.48 PM.png
     

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