RAM and CPU correlation

Discussion in 'Bukkit Help' started by Dothackking, Sep 13, 2012.

Thread Status:
Not open for further replies.
  1. Offline

    Dothackking

    Hi all. I've been running minecraft servers on and off (70+ slots) for years now. This is my fifth major one. I'm having problems in this one where the RAM usage and CPU usage seem to directly correlate. My map is about 3000x5000 if that matters.

    When I'm using under 1 gig of RAM, I'm using under 10% of CPU, but when I get near 10 gigs of my 16 gigs it is up to 100+%, which causes desync in movement and combat. This is not acceptable. The server is a 3.1 GHz quad core modern AMD cpu, I should not be having any issues with this.

    Does anyone know what is causing it, and how I can fix it?





    1. What OS are you using (Brand and version - Ex. Windows XP SP3)?

    EDT 2012 Linux

    2. What architecture is the OS you are running (x64 or x86)?
    x64
    3. What version and architecture is your java install? (Type: java -version in command prompt.)
    If you run any GNU/Linux, run this command to get all 3:

    java 1.7.0_06 64 bit.
    5. What build of CraftBukkit are you running? (do NOT say latest. Say the build number.)
    The build number is displayed in the top of the server.log.

    2352 (1.3.2 R0.1 I believe)

    6. What command are you using to run your CraftBukkit server?
    Code:
    screen -dmS minecraft java -Xms12G -Xmx12G -jar craftbukkit.jar nogui
    7. What plugins are you running?
    BadWater2
    BOSEconomy
    CitiTracer
    Citizens
    Factions
    Herochat
    Heroes
    HomeSpawnPlus
    JunkyardCreek
    lessfood
    LogBlock
    NoRain
    PermissionsBUkkit
    Sentry
    SimpleConceal
    SimpleHelpTickets
    TerrainControl
    TSA
    Vault
    VoxelSniper
    WeatherMan
    WorldEdit
    WorldGUard
    ZPort
    8. What error are you getting (post your server.log file)?
    [WARNING] Can't keep up! Did the system time change, or is the server overloaded
    9. What have you tried already?
    I have tried to replicate the problem on my local machine, but it only becomes evident once I start using over 5 gigs of RAM.
     
  2. Offline

    xS0u1zx

    When I'm using under 1 gig of RAM, I'm using under 10% of CPU, but when I get near 10 gigs of my 16 gigs it is up to 100+%, which causes desync in movement and combat. This is not acceptable. The server is a 3.1 GHz quad core modern AMD cpu, I should not be having any issues with this.

    Well there are a few different reasons why that could be happening. For one AMD processors make HORRIBLE server processors especially for heavy tasks like running something like a Minecraft server. Now how to explain this part um... If you are using less than a GB of RAM it's a clear indication there is not much activity going on thus why you wouldn't experience much CPU usage. If you are using 10GB however, the system is working hard not only caching all of the data but processing it as well. Using that much data also implies you are having a lot of player activity, chunk activity etc and etc and that would be why your CPU is maxing out when you are allocating that much ram.

    Now yes I understand you probably know all of this given your experience but the more RAM that you make available, the more your CPU works to allocate it. By default a database server is generally designed to reserve most if not all of the available RAM on a system for quick access, this is a productivity feature. You need to figure out a good balance between your RAM and CPU and stick with it. Yes RAM can actually allocate more information than the CPU can physically handle. So as I said before an AMD CPU is generally a very poor choice for server environments due to lack of horse power and true multitasking abilities which a server requires.
     
  3. Offline

    Dothackking

    I have done more testing, and while, in general it is RAM related, not always. I think this may be an issue I ran into while staffing HeroCraft, when players are too far apart it causes heavy CPU usage. We cut down the size of the map as much as we were easily willing to, but it still happens. Currently we're using 6 gigs of RAM and ~110% CPU.
    I can look into upgrading processors, but I'm not sure I can afford the upgrade, since I do these servers as a hobby.
     
Thread Status:
Not open for further replies.

Share This Page