Significance of 'migr' statistics shown in mpstat
One column of the 'mpstat' output is 'migr' - rate of "thread migrations (to another processor)". What is the significance of this statistic? What does it tell us if there are a lot of threads migration from this CPU to others? Or more outgoing migration on this CPU than on others?
Perhaps if there are a lot of outgoing migrations, coupled with a busy CPU, as shown in the "idl" (percent idel time) statistic, I may infer from it that because the CPU is busy with executing one of the threads, other threads are going to other idle CPUs. But there are also high 'migr' on other CPUs. Sometimes even higher than the busy CPU. I guess if both "outgoing migrations" and "incoming migrations" statistic are shown, things would be clearer. Anyway, how should we interpret the 'migr' statistic?
I have a dual-processor, dual core Opteron 270 node, i.e. 4 cores in total. When I am not running any user program, there are much more activity, in terms of 'intr' (interupts), 'ithr' (interrupts as threads), 'csw' (context switches), and 'icsw' (involuntary context switches), as shown on mpstat, on CPU0 than other 3 CPUs. Why does not Solaris 10 more evenly allocate the load on all 4 cores?
And who do 'interrupts as threads', 'involuntary context switches' mean?
