Load balancing for NUMA multiprocessors, in Linux kernel 2.6.30

mehta · 11-13-2009, 05:47 AM

I want to know how load balancing is done for NUMA Multiprocessors in Linux Kernel 2.6.30 etc. and how is it different from the Load balancing done in Linux kernel 2.6.8??

syg00 · 11-13-2009, 07:28 AM

There have been dozens of changes in that timeframe. Perhaps you'd better be a bit more specific in what you really want to know.
And why maybe.

mehta · 11-19-2009, 03:13 AM

1. in earlier kernel versions a periodic load balancing was done at every 200 ms. by each processor. Is it done the same way in current linux versions or there is some difference ?

2. Where can i get full documentation which describes all such details about Load Balancing in NUMA systems?

3. I want to know this because I am pursuing my research in this area.

syg00 · 11-24-2009, 05:10 PM

This is a function of the scheduler - the biggest change in your timeframe being the total rewrite of such. Now uses CFS (Completely Fair Scheduler) - google will get you plenty. I understand Ingo tossed out all the time-based metrics - he has published several articles, including in the source tree under ../Documentation/scheduler/. You might be interested in sched-domains.txt

Other than that you might be into searching the code itself or lkml.

mehta · 12-04-2009, 05:30 AM

i have gone through some of the documentation available, however still the difference in the load balancing methodologies adopted by linux 2.6.23 (and onwards) and prev. kernel versions is not clear. e.g., is rb-tree maintained for each processor or is it common for all the processors of the NUMA multiprocessor system ?
Pl. provide any information on these poiints, if you have.
Thanks.