> From: fangying > Sent: Monday, November 9, 2020 3:05 AM > To: peter.mayd...@linaro.org > Cc: qemu-devel@nongnu.org; qemu-...@nongnu.org; drjo...@redhat.com; > imamm...@redhat.com; shannon.zha...@gmail.com; alistair.fran...@wdc.com; > Zhanghailiang <zhang.zhanghaili...@huawei.com>; Salil Mehta > <salil.me...@huawei.com> > Subject: [RFC PATCH v3 03/13] hw/arm/virt: Replace smp_parse with one that > prefers cores > > From: Andrew Jones <drjo...@redhat.com> > > The virt machine type has never used the CPU topology parameters, other > than number of online CPUs and max CPUs. When choosing how to allocate > those CPUs the default has been to assume cores. In preparation for > using the other CPU topology parameters let's use an smp_parse that > prefers cores over sockets. We can also enforce the topology matches > max_cpus check because we have no legacy to preserve.
Hi Andrew, I am wondering if we need to take care of other levels of processor hierarchy as well in ARM64 like 'clusters'/'Dies'? Thanks > > Signed-off-by: Andrew Jones <drjo...@redhat.com> > --- > hw/arm/virt.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 76 insertions(+) > > diff --git a/hw/arm/virt.c b/hw/arm/virt.c > index ea24b576c6..ba902b53ba 100644 > --- a/hw/arm/virt.c > +++ b/hw/arm/virt.c > @@ -78,6 +78,8 @@ > #include "hw/virtio/virtio-iommu.h" > #include "hw/char/pl011.h" > #include "qemu/guest-random.h" > +#include "qapi/qmp/qerror.h" > +#include "sysemu/replay.h" > > #define DEFINE_VIRT_MACHINE_LATEST(major, minor, latest) \ > static void virt_##major##_##minor##_class_init(ObjectClass *oc, \ > @@ -2444,6 +2446,79 @@ static int virt_kvm_type(MachineState *ms, const char > *type_str) > return requested_pa_size > 40 ? requested_pa_size : 0; > } > > +/* > + * Unlike smp_parse() in hw/core/machine.c, we prefer cores over sockets, > + * e.g. '-smp 8' creates 1 socket with 8 cores. Whereas '-smp 8' with > + * hw/core/machine.c's smp_parse() creates 8 sockets, each with 1 core. > + * Additionally, we can enforce the topology matches max_cpus check, > + * because we have no legacy to preserve. > + */ > +static void virt_smp_parse(MachineState *ms, QemuOpts *opts) > +{ > + if (opts) { > + unsigned cpus = qemu_opt_get_number(opts, "cpus", 0); > + unsigned sockets = qemu_opt_get_number(opts, "sockets", 0); > + unsigned cores = qemu_opt_get_number(opts, "cores", 0); > + unsigned threads = qemu_opt_get_number(opts, "threads", 0); > + > + /* > + * Compute missing values; prefer cores over sockets and > + * sockets over threads. > + */ > + if (cpus == 0 || cores == 0) { > + sockets = sockets > 0 ? sockets : 1; > + threads = threads > 0 ? threads : 1; > + if (cpus == 0) { > + cores = cores > 0 ? cores : 1; > + cpus = cores * threads * sockets; > + } else { > + ms->smp.max_cpus = qemu_opt_get_number(opts, "maxcpus", > cpus); > + cores = ms->smp.max_cpus / (sockets * threads); > + } > + } else if (sockets == 0) { > + threads = threads > 0 ? threads : 1; > + sockets = cpus / (cores * threads); > + sockets = sockets > 0 ? sockets : 1; > + } else if (threads == 0) { > + threads = cpus / (cores * sockets); > + threads = threads > 0 ? threads : 1; > + } else if (sockets * cores * threads < cpus) { > + error_report("cpu topology: " > + "sockets (%u) * cores (%u) * threads (%u) < " > + "smp_cpus (%u)", > + sockets, cores, threads, cpus); > + exit(1); > + } > + > + ms->smp.max_cpus = qemu_opt_get_number(opts, "maxcpus", cpus); > + > + if (ms->smp.max_cpus < cpus) { > + error_report("maxcpus must be equal to or greater than smp"); > + exit(1); > + } > + > + if (sockets * cores * threads != ms->smp.max_cpus) { > + error_report("cpu topology: " > + "sockets (%u) * cores (%u) * threads (%u)" > + "!= maxcpus (%u)", > + sockets, cores, threads, > + ms->smp.max_cpus); > + exit(1); > + } > + > + ms->smp.cpus = cpus; > + ms->smp.cores = cores; > + ms->smp.threads = threads; > + ms->smp.sockets = sockets; > + } > + > + if (ms->smp.cpus > 1) { > + Error *blocker = NULL; > + error_setg(&blocker, QERR_REPLAY_NOT_SUPPORTED, "smp"); > + replay_add_blocker(blocker); > + } > +} > + > static void virt_machine_class_init(ObjectClass *oc, void *data) > { > MachineClass *mc = MACHINE_CLASS(oc); > @@ -2469,6 +2544,7 @@ static void virt_machine_class_init(ObjectClass *oc, > void > *data) > mc->cpu_index_to_instance_props = virt_cpu_index_to_props; > mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15"); > mc->get_default_cpu_node_id = virt_get_default_cpu_node_id; > + mc->smp_parse = virt_smp_parse; > mc->kvm_type = virt_kvm_type; > assert(!mc->get_hotplug_handler); > mc->get_hotplug_handler = virt_machine_get_hotplug_handler; > -- > 2.23.0