On 25/07/16 16:28, George Dunlap wrote: > The initial placement algorithm sometimes picks cpus outside of the > mask it's given, does a lot of unnecessary bitmasking, does its own > separate load calculation, and completely ignores vcpu hard and soft > affinities. Just get rid of it and rely on the schedulers to do > initial placement. > > Signed-off-by: George Dunlap <george.dun...@citrix.com> > --- > v2: > - Use cpumask_any() to avoid a bias towards low pcpus on schedulers > that prefer to leave the cpu where it is. > > The core problem with default_vcpu0_location() is that it chooses its > initial cpu based on the sibling of pcpu 0, not the first available > sibling in the online mask; so if pcpu 1 ends up being less "busy" > than all the cpus in the pool, then it ends up being chosen even > though it's not in the pool. > > Fixing the algorithm would involve starting with the sibling map of > cpumask_first(online) rather than 0, and then having all sibling > checks not only test that the result of cpumask_next() < nr_cpu_ids, > but that the result is in online. > > Additionally, as far as I can tell, the cpumask_test_cpu(i, > &cpu_exclude_map) at the top of the for_each_cpu() loop can never > return false; and this both this test and the cpumask_or() are > unnecessary and should be removed. > > CC: Dario Faggioli <dario.faggi...@citrix.com> > CC: Anshul Makkar <anshul.mak...@citrix.com> > CC: Meng Xu <men...@cis.upenn.edu> > CC: Andrew Cooper <andrew.coop...@citrix.com> > CC: Ian Jackson <ian.jack...@eu.citrix.com> > CC: Jan Beulich <jbeul...@suse.com> > CC: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> > CC: Stefano Stabellini <sstabell...@kernel.org> > CC: Tim Deegan <t...@xen.org> > CC: Wei Liu <wei.l...@citrix.com>
Acked-by: Andrew Cooper <andrew.coop...@citrix.com> from a REST point of view. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
