On Wed, 29 Mar 2017 13:24:49 +1100 David Gibson <da...@gibson.dropbear.id.au> wrote:
> On Tue, Mar 28, 2017 at 12:53:10PM +0200, Igor Mammedov wrote: > > On Tue, 28 Mar 2017 15:19:20 +1100 > > David Gibson <da...@gibson.dropbear.id.au> wrote: > > > > > On Wed, Mar 22, 2017 at 02:32:30PM +0100, Igor Mammedov wrote: > > > > Originally CPU threads were by default assigned in > > > > round-robin fashion. However it was causing issues in > > > > guest since CPU threads from the same socket/core could > > > > be placed on different NUMA nodes. > > > > Commit fb43b73b (pc: fix default VCPU to NUMA node mapping) > > > > fixed it by grouping threads within a socket on the same node > > > > introducing cpu_index_to_socket_id() callback and commit > > > > 20bb648d (spapr: Fix default NUMA node allocation for threads) > > > > reused callback to fix similar issues for SPAPR machine > > > > even though socket doesn't make much sense there. > > > > > > > > As result QEMU ended up having 3 default distribution rules > > > > used by 3 targets /virt-arm, spapr, pc/. > > > > > > > > In effort of moving NUMA mapping for CPUs into possible_cpus, > > > > generalize default mapping in numa.c by making boards decide > > > > on default mapping and let them explicitly tell generic > > > > numa code to which node a CPU thread belongs to by replacing > > > > cpu_index_to_socket_id() with @cpu_index_to_instance_props() > > > > which provides default node_id assigned by board to specified > > > > cpu_index. > > > > > > > > Signed-off-by: Igor Mammedov <imamm...@redhat.com> > [snip] > > > > +static CpuInstanceProperties > > > > +virt_cpu_index_to_props(MachineState *ms, unsigned cpu_index) > > > > +{ > > > > + MachineClass *mc = MACHINE_GET_CLASS(ms); > > > > + const CPUArchIdList *possible_cpus = mc->possible_cpu_arch_ids(ms); > > > > + > > > > + assert(cpu_index < possible_cpus->len); > > > > + return possible_cpus->cpus[cpu_index].props;; > > > > +} > > > > + > > > > > > It seems a bit weird to have a machine specific hook to pull the > > > property information when one way or another it's coming from the > > > possible_cpus table, which is already constructed by a machine > > > specific hook. Could we add a range or list of cpu_index values to > > > each possible_cpus entry instead, and have a generic lookup of the > > > right entry based on that? > > [snip] > > > > -static unsigned pc_cpu_index_to_socket_id(unsigned cpu_index) > > > > +static CpuInstanceProperties > > > > +pc_cpu_index_to_props(MachineState *ms, unsigned cpu_index) > > > > { > > > > - X86CPUTopoInfo topo; > > > > - x86_topo_ids_from_idx(smp_cores, smp_threads, cpu_index, > > > > - &topo); > > > > - return topo.pkg_id; > > > > + MachineClass *mc = MACHINE_GET_CLASS(ms); > > > > + const CPUArchIdList *possible_cpus = mc->possible_cpu_arch_ids(ms); > > > > + > > > > + assert(cpu_index < possible_cpus->len); > > > > + return possible_cpus->cpus[cpu_index].props;; > > > > > > Since the pc and arm version of this are basically identical, I wonder > > > if that should actually be the default implementation. If we need it > > > at all. > > ARM is still moving target and props are not really defined for it yet, > > so I'd like to keep it separate for now and when it stabilizes we can think > > about generalizing it. > > Fair enough. > > Any thoughts on my more general query above None so far.