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What Are Typical Load Averages for Servers?

Posted by Cliff on from the deciphering-the-numbers dept.

Jon Hill asks: "I'm curious to figure out how to guage the performance of my servers and know at what level of usage I should think about hardware upgrades. 90% of our servers run Linux and various services standard to Linux such as sendmail, samba, DNS, etc. One of our main servers (router/firewall/sendmail/spop) has been running with a load average of .5 to 1.5 regularly. It supports 200 users and is an SMP Intel machine with 2GB of RAM. I'm not sure if it needs software/kernel tweaking or hardware modifications and I can't seem to find any reference information. Suggestions?"

2 of 25 comments (clear)

  1. Upgrade your hardware iff: by randombit · · Score: 2, Insightful

    1) Users are complaining because it's too slow
    AND
    2) You actually have nothing better to spend it on; unless you are very lucky, this one is not true.
    AND
    3) Software tweaking isn't doing any good.

    OTOH, tweaking the kernel and such is always fun. Here are a few ideas:

    1) Recompile the latest 'stable' kernel optimized for your machine. 2.4.2 -> 2.4.12 produces a huge increase in I/O performance on my machine, for example. You may find out something similiar.

    2) Related thing: BIOS updates and tweaking can sometimes go a long way.

    3) Upgrade the machine to the latest distro; a nice thing about Unix is things usually get faster, not slower.

    4) Figure out what is using your CPU time. For example, given you're running SPOP, I suspect a lot of that time is used for SSL. So recompile OpenSSL with better optimizations (the normal OpenSSL RPMs are always underpowered; asm is disabled, no -march flags, etc), and you should see a magical increase in performance.

    5) Assuming this makes your system faster, celebrate by spending some of the money you would have used to upgrade on beer.

  2. General recommendation... by larien · · Score: 3, Insightful
    As a general recommendation I heard once, your load average shouldn't get more that 2xnumber of CPUs. i.e. on a single CPU box, it shouldn't get higher than 2, for a 64-CPU high-powered server, it shouldn't get above 128.

    I've found it a reasonably good guide to when there's an issue on Solaris boxes; I think linux uses similar numbers to calculate run queue averages, but other OS's (eg, IRIX) use different formulas to calcualte it so you might need to tweak this recommendation.