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Load numbers
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Load numbers

drmikedrmike Member
edited August 2011 in General

Dumb question:

http://www.lowendbox.com/blog/quickweb-4-99-300mb-openvz-vps-in-la-phoenix-uk-and-germany/#comment-43460

I thought when looking at the load numbers within a top, you're looking at your own load number? At least with Xen.

Comments

  • You are looking at your own load avg on most VPSs, but if there as a few abusers on the node yours can be even be 20 with nothing running except sshd.

    FreeVPS.us - The oldest post to host VPS provider
  • Maybe I'm misunderstanding here. When I do a top, I'm looking at my load. Right?

  • Yes.

  • KuJoeKuJoe Member, Provider

    Yes you are but your load is affected by other VPSs on the server. We had one client who's load was 60.00 but when we checked his VPS he was only running 6 processes (the load was due to another VPS using a massive amount of disk I/O which caused even the slightest processing on the server to "spike").

    -Joe @ SecureDragon - LEB's Powered by Wyvern in FL, CO, CA, IL, NJ, GA, OR, TX, and AZ
    Need backup space? Check out BackupDragon
  • drmikedrmike Member
    edited August 2011

    So in other words, other people's loads could show up in mine, right? Does that only happen inn OpenVZ or all of them?

  • When you look at top your seeing the load you are putting on the host node.

    For example if there are two guests on a OpenVZ node. Guest #1 is has a load of 5 and Guest #2 has a load of 1 and guest #2 looks at his load then he will see a load of 1. Not a load of 6.

    And a load of 5 from guest #1 is really a true load of 5 because of how much of a slice they have of the CPU. If there were 10 guests all showing a load of 2 each and I check the host load I'm not going to see a load of 20. I'm going to see somewhere around 12 or so.

    KuJoe: Your correct in saying that other guests on the host node will create a load for other users but they are not going to see their neighbors load in their instance. What they will see and what I think correctly states what your discussing is I/O wait in top.

    Which is how many seconds the kernel has work to do but is having to wait on the processor to do it. Generally a high I/O wait is indicative of a loaded storage subsystem.

    The nature of a high density virtualization is that from time to time you will see I/O wait simply because the drive activity is sustained and random from all of the guests. A small amount can be tolerated but continously high waits will slow things down for everyone. Examples of this which I've seen are typing in a command and having to wait a few seconds after I hit enter for something simple to process.

    You can open two SSH sessions to your instance and use one to watch TOP and then issue commands in the other and watch just what impact you have. The LEB gold standard "drive beat down" of DD will really show you some fun with I/O waits. ;)

    Brandon

  • ztecztec Member

    What are acceptable load averages?
    I already freak out when it's over 1.00, cause a second waiting time seems like a long time for a webserver. This concerns dedicated servers btw...

    You can spam me with any yearly shared hosting deal.

  • skagerrakskagerrak Member
    edited August 2011

    Single-CPU: A load of 1 shows that all processes can be handled by the CPU. More means an overload (most time I/O-wait), less means underload, hence, idling of CPU. From an economical point of view a load of 1 is perfect. From an IT-point of view it depends. Multiple-CPU: Load/CPU.

  • KuJoe said: We had one client who's load was 60.00 but when we checked his VPS he was only running 6 processes

    How does it even make sense, as loadavg 60 means there are 60 processes currently in run-queue or waiting for IO. Where do you get 60 processes when you only have 6? I would think that in this case loadavg would be capped at 6?

    Blog at LowEndBox.com.

  • drmikedrmike Member
    edited August 2011

    That's what's throwing me off as well.

    If I see a 60 load, I'd be raising hell about it. edit: Plus threatening them with sending over gerard depardieu as well. :)

  • ztecztec Member

    skagerrak said: Single-CPU: A load of 1 shows that all processes can be handled by the CPU. More means an overload (most time I/O-wait), less means underload, hence, idling of CPU. From an economical point of view a load of 1 is perfect. From an IT-point of view it depends. Multiple-CPU: Load/CPU.

    So on a Quad core CPU, a load of 4 -- would be perfect?

    You can spam me with any yearly shared hosting deal.

  • It would mean that every process could be handled by a Core of the CPU, yes. If it is perfect from an technical point of view depends on your planning.

  • @ztec : It's not perfect, as you don't have headroom for further tasks and each processor is already pre-occupied by the tasks they have.

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