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  1. #1
    Master Untangler carboncow's Avatar
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    Default CPU Load vs. Usage?

    First, is there good documentation on explaining reports that I missed somewhere?

    1. My CPU load report is below 3 on all intervals and I suspect it to be low these days as our business doesn't get hoping till September. I'm guessing this is not a % but rather Untangle's own index for load? If so what is the full scale?

    2. CPU "usage" hits 100% a bit for "user" and doesn't go above 15% for system. I don't know much about linux but what is system vs. user mean? Is user Untangle and system is the Linux OS processes?

    This is all on a P4 3.0 with 4gig of RAM with SATA Raid1

  2. #2
    Untangler
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    Default

    I'd be interested in info on this as well. I see something similar, but not as high as your CPU Usage. Mine runs about half of these numbers.

  3. #3
    Untangle Ninja jcoehoorn's Avatar
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    Default

    There's a lot of factors, and I don't know most of them, but one I do know is that it's per cpu. So, for example, a consistent load of 3.8 might mean nothing for a quad core but be death for your single core p4.

    I tend to think of it as a way to measure how much work untangle is currently doing and therefore how quickly it can statrt processing new sessions that come in. As long as the number is less than 1/cpu core, there's cpu time available immediately for the new sessions.

    There're more to it than cpu time, though. I'm in desperate need of a bandwidth upgrade, and I'll see my load spike up to 5 or 7 at times when I have a quad core box with 2 of the cpus sitting mostly idle. This is because I don't have enough bandwidth to serve all the waiting sessions, and so there's a queue of sorts.
    Five time Microsoft ASP.Net MVP managing a Lenovo RD330 / E5-2420 / 16GB with Untangle 14.2.2 to protect 500Mbits for ~450 residential college students and associated staff and faculty

  4. #4
    Master Untangler carboncow's Avatar
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    jcoehoorn,

    several questions:

    1. How would you upgrade your bandwidth as far as the box is concerned? Are you talking multiple firewalls with load balancing then? Looking at your footer you have quite a few more power users then my small business.

    2. I'm averaging below 1 on the index (see above screenshots) but seeing spikes of 2 at times. As stated our business model (ski resort) is low this time of year with less then a dozen users hitting the net right now but we'll spike in the winter due to people accessing our webcams which you know is heavy on bandwidth.

    3. Are you stating to dived the value by the number of cores to get the true value to review? Thus (in your example) a value of 3.8 on a quad core is a .95 then? And thus under your recommended 1.0. I know the one setting in the box doesn't start dropping work until it hits 10 or 11 in value.

  5. #5
    Untangle Ninja jcoehoorn's Avatar
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    Default

    Answers:

    1. You contact your ISP. Where I'm at, we currently have a 20mbit fiber connection. I'd like to bumpt that to 40mbit, but I haven't been able to get reasonable pricing on the upgrade yet. If this fails, untangle has WAN Balancer and WAN Failover apps. I can plug multiple internet links in (external interfaces) to untangle using those apps and share them both among my users.

    2. I think you'll be okay, but it's hard to say. Untangle has features like Bandwidth Control and Attack Blocker that allow it to be very effective at portioning out the available bandwidth and cpu load. It helps that you have plenty of RAM, but you might want to think about getting a box with a real dual-core processor before the season hits, just as insurance.

    3. That's sort of right. A 3.8 on a quad core is still a 3.8, though, because it means you're doing that much more work.
    Five time Microsoft ASP.Net MVP managing a Lenovo RD330 / E5-2420 / 16GB with Untangle 14.2.2 to protect 500Mbits for ~450 residential college students and associated staff and faculty

  6. #6
    Master Untangler carboncow's Avatar
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    All great info and you have reminded me to consider a more modern box. This was a $90 server from ebay for testing and just assumed it wold work until I saw the beefer requirements (post install) then our previous low tech solution.

    What is your hard drive configuration on your firewall?

    I may find a another cheap dell powerdge quad core (we have several around here) that I can load up with 8 gigs of ram for $300. What is the word on the street of the best RAIL level with Untangle. I don't recall need redundancy since you can get another box running in a pinch easily in the case of major failure...is Raid0 worth it or stay safe with a Raid1 or Raid5?

  7. #7
    some dude hlarsen's Avatar
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  8. #8
    Untangle Junkie dmorris's Avatar
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    lol. this guy is very confused and his analogies are terrible.

    firstly, the load is based on the length of things *waiting* in the run queue.
    secondly, the run queue is a single queue - a single-lane road in his analogy no matter how many cores you have.

    Ultimately tasks come off the front of the run queue much faster (you hope) because you have more cores grabbing tasks off the queue, but this is also true if you double your processor speed but you don't see people telling you do divide load by your processor clock rate. The important thing is "on average how many tasks are waiting around to be run at any given time."

    In other words you don't care how many checkers are checking out customers in the checkout line, or whether each one is fast or slow. You ultimately care about how many customers are standing around waiting. If its 5 at any given time - its 5. It doesn't matter how many checkout counters you have or how fast your checkers are.

    somewhat ironically, the articles he links explain this quite well.
    Last edited by dmorris; 09-09-2011 at 08:17 AM.
    cdoublejj likes this.
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  9. #9
    some dude hlarsen's Avatar
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    lol i thought i saw you post that article last year; quick search shows it was a random.

  10. #10
    Untangle Junkie dmorris's Avatar
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    I've been looking for a good article on this for a while.

    The problem is that most of them are written to help determine how much each CPU is utilized. Which is entirely the wrong question to ask. (In this case you DO need to divide by the number of cores).

    The question to ask is "How busy is my system?" in which case you care about the number of processes waiting at any given time (on average) regardless of CPU count and speed.

    edit:
    as per our discussion yesterday in the user experience meeting, we're going to be removing % utilization numbers as they are confusing people.
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