virtio-blk and virtio-scsi devices will need a way to specify the
mapping between IOThreads and virtqueues. At the moment all virtqueues
are assigned to a single IOThread or the main loop. This single thread
can be a CPU bottleneck, so it is necessary to allow finer-grained
assignment to spread the load.
Introduce DEFINE_PROP_IOTHREAD_VQ_MAPPING_LIST() so devices can take a
parameter that maps virtqueues to IOThreads. The command-line syntax for
this new property is as follows:
--device
'{"driver":"foo","iothread-vq-mapping":[{"iothread":"iothread0","vqs":[0,1,2]},...]}'
IOThreads are specified by name and virtqueues are specified by 0-based
index.
It will be common to simply assign virtqueues round-robin across a set
of IOThreads. A convenient syntax that does not require specifying
individual virtqueue indices is available:
--device
'{"driver":"foo","iothread-vq-mapping":[{"iothread":"iothread0"},{"iothread":"iothread1"},...]}'
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
qapi/virtio.json | 29 ++++++++++++++++++
include/hw/qdev-properties-system.h | 5 ++++
hw/core/qdev-properties-system.c | 46 +++++++++++++++++++++++++++++
3 files changed, 80 insertions(+)
diff --git a/qapi/virtio.json b/qapi/virtio.json
index e6dcee7b83..19c7c36e36 100644
--- a/qapi/virtio.json
+++ b/qapi/virtio.json
@@ -928,3 +928,32 @@
'data': { 'path': 'str', 'queue': 'uint16', '*index': 'uint16' },
'returns': 'VirtioQueueElement',
'features': [ 'unstable' ] }
+
+##
+# @IOThreadVirtQueueMapping:
+#
+# Describes the subset of virtqueues assigned to an IOThread.
+#
+# @iothread: the id of IOThread object
+#
+# @vqs: an optional array of virtqueue indices that will be handled by this
+# IOThread. When absent, virtqueues are assigned round-robin across all
+# IOThreadVirtQueueMappings provided. Either all IOThreadVirtQueueMappings
+# must have @vqs or none of them must have it.
+#
+# Since: 9.0
+##
+
+{ 'struct': 'IOThreadVirtQueueMapping',
+ 'data': { 'iothread': 'str', '*vqs': ['uint16'] } }
+
+##
+# @DummyVirtioForceArrays:
+#
+# Not used by QMP; hack to let us use IOThreadVirtQueueMappingList internally
+#
+# Since: 9.0
+##
+
+{ 'struct': 'DummyVirtioForceArrays',
+ 'data': { 'unused-iothread-vq-mapping': ['IOThreadVirtQueueMapping'] } }
diff --git a/include/hw/qdev-properties-system.h
b/include/hw/qdev-properties-system.h
index 91f7a2452d..06c359c190 100644
--- a/include/hw/qdev-properties-system.h
+++ b/include/hw/qdev-properties-system.h
@@ -24,6 +24,7 @@ extern const PropertyInfo qdev_prop_off_auto_pcibar;
extern const PropertyInfo qdev_prop_pcie_link_speed;
extern const PropertyInfo qdev_prop_pcie_link_width;
extern const PropertyInfo qdev_prop_cpus390entitlement;
+extern const PropertyInfo qdev_prop_iothread_vq_mapping_list;
#define DEFINE_PROP_PCI_DEVFN(_n, _s, _f, _d) \
DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_pci_devfn, int32_t)
@@ -82,4 +83,8 @@ extern const PropertyInfo qdev_prop_cpus390entitlement;
DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_cpus390entitlement, \
CpuS390Entitlement)
+#define DEFINE_PROP_IOTHREAD_VQ_MAPPING_LIST(_name, _state, _field) \
+ DEFINE_PROP(_name, _state, _field, qdev_prop_iothread_vq_mapping_list, \
+ IOThreadVirtQueueMappingList *)
+
#endif
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 73cced4626..1a396521d5 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -18,6 +18,7 @@
#include "qapi/qapi-types-block.h"
#include "qapi/qapi-types-machine.h"
#include "qapi/qapi-types-migration.h"
+#include "qapi/qapi-visit-virtio.h"
#include "qapi/qmp/qerror.h"
#include "qemu/ctype.h"
#include "qemu/cutils.h"
@@ -1160,3 +1161,48 @@ const PropertyInfo qdev_prop_cpus390entitlement = {
.set = qdev_propinfo_set_enum,
.set_default_value = qdev_propinfo_set_default_value_enum,
};
+
+/* --- IOThreadVirtQueueMappingList --- */
+
+static void get_iothread_vq_mapping_list(Object *obj, Visitor *v,
+ const char *name, void *opaque, Error **errp)
+{
+ IOThreadVirtQueueMappingList **prop_ptr =
+ object_field_prop_ptr(obj, opaque);
+
+ visit_type_IOThreadVirtQueueMappingList(v, name, prop_ptr, errp);
+}
+
+static void set_iothread_vq_mapping_list(Object *obj, Visitor *v,
+ const char *name, void *opaque, Error **errp)
+{
+ IOThreadVirtQueueMappingList **prop_ptr =
+ object_field_prop_ptr(obj, opaque);
+ IOThreadVirtQueueMappingList *list;
+
+ if (!visit_type_IOThreadVirtQueueMappingList(v, name, &list, errp)) {
+ return;
+ }
+
+ qapi_free_IOThreadVirtQueueMappingList(*prop_ptr);
+ *prop_ptr = list;
+}
+
+static void release_iothread_vq_mapping_list(Object *obj,
+ const char *name, void *opaque)
+{
+ IOThreadVirtQueueMappingList **prop_ptr =
+ object_field_prop_ptr(obj, opaque);
+
+ qapi_free_IOThreadVirtQueueMappingList(*prop_ptr);
+ *prop_ptr = NULL;
+}
+
+const PropertyInfo qdev_prop_iothread_vq_mapping_list = {
+ .name = "IOThreadVirtQueueMappingList",
+ .description = "IOThread virtqueue mapping list [{\"iothread\":\"<id>\", "
+ "\"vqs\":[1,2,3,...]},...]",
+ .get = get_iothread_vq_mapping_list,
+ .set = set_iothread_vq_mapping_list,
+ .release = release_iothread_vq_mapping_list,
+};
--
2.43.0
