On Tue, Aug 03, 2021 at 10:26:46AM +0200, Pierre Morel wrote: > Now that the PTF instruction is interpreted by the SIE we can optimize > the arch_update_cpu_topology callback to check if there is a real need > to update the topology by using the PTF instruction. > > Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx> > --- > arch/s390/kernel/topology.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c > index 26aa2614ee35..741cb447e78e 100644 > --- a/arch/s390/kernel/topology.c > +++ b/arch/s390/kernel/topology.c > @@ -322,6 +322,9 @@ int arch_update_cpu_topology(void) > struct device *dev; > int cpu, rc; > > + if (!ptf(PTF_CHECK)) > + return 0; > + We have a timer which checks if topology changed and then triggers a call to arch_update_cpu_topology() via rebuild_sched_domains(). With this change topology changes would get lost.
