central-processing-unitcpu-usageubuntu-10.04
Is load average related to CPU ThreadS OR CPU core?
i am having a xenon cpu with 8 cores and 16 threads.
How much can be the acceptable load average?
Sometimes Load AVerage reaches 11.
so does that means load average upto 16 is with in acceptable range.
Set the lowest number of vCPUs your servers need to perform their function, don't over-allocate them or you could easily slow down your VMs.
I generally think of a HyperThreaded core as being 20%-30% of a real core, depending on how effectively your application can leverage multiple threads. They are considered in load average and load average thresholds.
Here's an example of a dual-socket Intel X5570 Nehalem system before and after enabling Hyperthreading. The OS is CentOS 5.8. The actual average system run queue/load average did not change substantially (the app is pretty much single-threaded), but the load threshold did.
That said, there are many times when I disable HyperThreading... For my low-latency and deterministic applications, I want finer control of where application resources are scheduled. There's a penalty for going to a HyperThread core in those cases. Also, I have one particular situation where the application is running on a 4-socket 8-core CPU that has HyperThreading. It's way too many cores... so I just disabled HT to cut from 64 logical CPU's to 32.
Best Answer
HyperThreaded CPU cores aren't quite full CPU cores, so I'd probably be concerned around a load of 12 or so on a system with 8 physical cores. From a monitoring perspective, your load threshold is technically 16.
Of course, this all depends on what's causing the load increase. If it's all CPU-processing activity, that's different than if some component of the high load is the result of the I/O subsystem and storage.