SMF Support > Server Performance and Configuration

Server Load

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Melissa524:
As this is my first time ever owning my own server, I am not sure about what is good or what is bad when it comes to server load.  I assume the lower the number the better but I am not sure what the scale is.  For example:  My avg server load is 2.09.  Is this a good or bad server load?  Does it go up by .1 or .001?  Stuff like that.

Arantor:
The number is mostly a voodoo thing. There *are* people who understand what the number actually *means* but yes, generally, lower = better.

Thing is, the number on its own doesn't tell you much. Running just SMF? How many users active at once?

butch2k:
It also depends on the number of cpus (as seen by the os) you have. A load of 2 when you have 8 cpus is a low load but with only a single core cpu it's a high load.
Usualy it's consided good to have a load average under the number of cpus installed, but a well configured server could cope with a cpus x 2 load or more.

nend:
That is about right from my understanding. The multi-core CPU's though have really complicated everything. 1 is basically 1x what your CPU can handle, please remember this is just a single core. If you have multiple cores then you can take say like 4 cores then a load average of 4 is basically 1x what your multi-core CPU can handle.

Anything over is processes that have to wait for a turn at the CPU. You can go over the load average but don't let it do it for too long.

One thing that has me really confused though is the ARM CPU's, mine the load average always displays high and if that was the truth the system wouldn't be stable for long. Has to be something different about those ARM's.

CoreISP:
The thing is it also depends on utilization. That's where top jumps to the rescue to see what's going on.
The "stairs" in which load is determined is easy to understand, but sometimes it's a bit... flawed imho.

For example if a very tiny script forked too many times (bad scripting) you can see the load being extremely high, yet the server is fast as hell and CPU utilization is actually not bad. I've seen servers with a load of 2000+ but still performing like a beast :P Yet under normal circumstances, a quadcore CPU with a load of say 6.00 could slowly start lagging if it still goes up. Quite the difference.

In general with any CPU 2.00 load is probably acceptable and without knowing which processes are running: it is impossible to say whether or not it is a high load for what it is doing or it is perfectly normal. Just looking at the CPU load will not tell you everything. While it may give a reasonable idea, you have to look in to the rest of the statistics to find out if it truly is a performance related thing or not.
By looking at a train, you can determine if it goes fast or slow, right? However, just by solely looking at it you can't determine the actual accurate speed in miles or kilometers per hour it runs at. Catch my drift?

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