On Tue, Jan 07, 2014 at 01:59:30PM +0100, Peter Zijlstra wrote: > On Tue, Jan 07, 2014 at 12:55:18PM +0000, Morten Rasmussen wrote: > > My understanding is that should_we_balance() decides which cpu is > > eligible for doing the load balancing for a given domain (and the > > domains above). That is, only one cpu in a group is allowed to load > > balance between the local group and other groups. That cpu would > > therefore be reponsible for pulling enough load that the groups are > > balanced even if it means temporarily overloading itself. The other cpus > > in the group will take care of load balancing the extra load within the > > local group later. > > Correct.
On that; one of the things I wanted to (and previously did attempt but failed) is trying to rotate this cpu. Currently its always the first cpu (of the group) and that gives a noticeable bias. If we could slowly rotate the cpu that does this that would alleviate both the load and cost bias. One thing I was thinking of is keeping a global counter maybe: 'x := jiffies >> n' might be good enough and using the 'x % nr_cpus_in_group'-th cpu instead. Then again, these are micro issue and not a lot of people complain about this. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
