On Fri, Nov 22, 2019 at 10:45:08AM +0000, Alexandru Elisei wrote:
> Hi,
>
> On 11/20/19 2:19 PM, Andrew Jones wrote:
> > We can only use online cpus, so make sure we check specifically for
> > those.
> >
> > Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
> > ---
> > scripts/runtime.bash | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/scripts/runtime.bash b/scripts/runtime.bash
> > index 200d5b67290c..fbad0bd05fc5 100644
> > --- a/scripts/runtime.bash
> > +++ b/scripts/runtime.bash
> > @@ -1,5 +1,5 @@
> > : "${RUNTIME_arch_run?}"
> > -: ${MAX_SMP:=$(getconf _NPROCESSORS_CONF)}
> > +: ${MAX_SMP:=$(getconf _NPROCESSORS_ONLN)}
>
> I tested it on my machine by offlining a CPU and calling getconf _NPROCESSORS_CONF
> (returned 32) and getconf _NPROCESSORS_ONLN (returned 31). man 3 sysconf also
> agrees with your patch.
>
> I am wondering though, if _NPROCESSORS_CONF is 8 and _NPROCESSORS_ONLN is 1
> (meaning that 7 CPUs were offlined), that means that qemu will create 8 VCPUs
> which will share the same physical CPU. Is that undesirable?
With KVM enabled that's not recommended. KVM_CAP_NR_VCPUS returns the
number of online VCPUs (at least for arm). Since the guest code may not
run as expected with overcommitted VCPUs we don't usually want to test
that way. OTOH, maybe we should write a test or two that does run with
overcommitted VCPUs in order to look for bugs in KVM.
Thanks,
drew
>
> Thanks,
> Alex
> > : ${TIMEOUT:=90s}
> >
> > PASS() { echo -ne "\e[32mPASS\e[0m"; }
>
