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[RFC PATCH v2 03/13] hw/arm/virt: Replace smp_parse with one that prefer
From: |
Ying Fang |
Subject: |
[RFC PATCH v2 03/13] hw/arm/virt: Replace smp_parse with one that prefers cores |
Date: |
Tue, 20 Oct 2020 21:14:30 +0800 |
From: Andrew Jones <drjones@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.
Signed-off-by: Andrew Jones <drjones@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
- [RFC PATCH v2 10/13] target/arm/cpu: Add CPU cache description for arm, (continued)
- [RFC PATCH v2 10/13] target/arm/cpu: Add CPU cache description for arm, Ying Fang, 2020/10/20
- [RFC PATCH v2 07/13] hw/arm/virt-acpi-build: distinguish possible and present cpus Message, Ying Fang, 2020/10/20
- [RFC PATCH v2 08/13] hw/acpi/aml-build: add processor hierarchy node structure, Ying Fang, 2020/10/20
- [RFC PATCH v2 12/13] hw/acpi/aml-build: build ACPI CPU cache hierarchy information, Ying Fang, 2020/10/20
- [RFC PATCH v2 06/13] hw/arm/virt: DT: add cpu-map, Ying Fang, 2020/10/20
- [RFC PATCH v2 05/13] hw: add compat machines for 5.3, Ying Fang, 2020/10/20
- [RFC PATCH v2 03/13] hw/arm/virt: Replace smp_parse with one that prefers cores,
Ying Fang <=
- [RFC PATCH v2 04/13] device_tree: Add qemu_fdt_add_path, Ying Fang, 2020/10/20
- [RFC PATCH v2 09/13] hw/arm/virt-acpi-build: add PPTT table, Ying Fang, 2020/10/20
- [RFC PATCH v2 13/13] hw/arm/virt-acpi-build: Enable CPU cache topology, Ying Fang, 2020/10/20