On Fri, Feb 24, 2023 at 08:23:40AM +0000, Yangming wrote:
Optimize the virtio-balloon feature on the ARM platform by adding a
variable to keep track of the current hot-plugged pc-dimm size, instead of
traversing the virtual machine's memory modules to count the current RAM
size during the balloon inflation or deflation process. This variable can be
updated only when plugging or unplugging the device, which will result in an
increase of more than 60% efficiency of balloon process on the ARM platform.
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Ming Yang yangming73@huawei.com
What kind of performance gains are achieved by this patch?
Pls include some measurements: before and after.
---
hw/mem/pc-dimm.c | 2 ++
hw/virtio/virtio-balloon.c | 44 +++++++++++++-------------------------
include/hw/boards.h | 1 +
3 files changed, 18 insertions(+), 29 deletions(-)
diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c index
50ef83215c..192fc7922c 100644
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -81,6 +81,7 @@ void pc_dimm_plug(PCDIMMDevice *dimm,
MachineState *machine)
memory_device_plug(MEMORY_DEVICE(dimm), machine);
vmstate_register_ram(vmstate_mr, DEVICE(dimm));
+ machine->device_memory->dimm_size += vmstate_mr->size;
}
void pc_dimm_unplug(PCDIMMDevice *dimm, MachineState *machine)
@@ -90,6 +91,7 @@ void pc_dimm_unplug(PCDIMMDevice *dimm,
MachineState *machine)
memory_device_unplug(MEMORY_DEVICE(dimm), machine);
vmstate_unregister_ram(vmstate_mr, DEVICE(dimm));
+ machine->device_memory->dimm_size -= vmstate_mr->size;
}
static int pc_dimm_slot2bitmap(Object *obj, void *opaque) diff --git
a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index
746f07c4d2..40fa40109d 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -729,37 +729,14 @@ static void virtio_balloon_get_config(VirtIODevice
*vdev, uint8_t *config_data)
memcpy(config_data, &config, virtio_balloon_config_size(dev)); }
-static int build_dimm_list(Object *obj, void *opaque) -{
- GSList **list = opaque;
-
- if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
- DeviceState *dev = DEVICE(obj);
- if (dev->realized) { /* only realized DIMMs matter */
- *list = g_slist_prepend(*list, dev);
- }
- }
-
- object_child_foreach(obj, build_dimm_list, opaque);
- return 0;
-}
-
static ram_addr_t get_current_ram_size(void) {
- GSList *list = NULL, *item;
- ram_addr_t size = current_machine->ram_size;
-
- build_dimm_list(qdev_get_machine(), &list);
- for (item = list; item; item = g_slist_next(item)) {
- Object *obj = OBJECT(item->data);
- if (!strcmp(object_get_typename(obj), TYPE_PC_DIMM)) {
- size += object_property_get_int(obj, PC_DIMM_SIZE_PROP,
- &error_abort);
- }
+ MachineState *machine = MACHINE(qdev_get_machine());
+ if (machine->device_memory != NULL) {
+ return machine->ram_size + machine->device_memory->dimm_size;
+ } else {
+ return machine->ram_size;
}
- g_slist_free(list);
-
- return size;
}
static bool virtio_balloon_page_poison_support(void *opaque) @@ -776,7
+753,11 @@ static void virtio_balloon_set_config(VirtIODevice *vdev,
VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
struct virtio_balloon_config config;
uint32_t oldactual = dev->actual;
- ram_addr_t vm_ram_size = get_current_ram_size();
+ ram_addr_t vm_ram_size;
+ ram_addr_t vm_ram_size_new;
+
+retry:
+ vm_ram_size = get_current_ram_size();
memcpy(&config, config_data, virtio_balloon_config_size(dev));
dev->actual = le32_to_cpu(config.actual); @@ -784,6 +765,11 @@ static
void virtio_balloon_set_config(VirtIODevice *vdev,
qapi_event_send_balloon_change(vm_ram_size -
((ram_addr_t) dev->actual <<
VIRTIO_BALLOON_PFN_SHIFT));
}
+ vm_ram_size_new = get_current_ram_size();
+ if (vm_ram_size_new != vm_ram_size) {
+ goto retry;
+ }
+
What is this doing? needs and comment.
And please don't implement loops using goto.
dev->poison_val = 0;
if (virtio_balloon_page_poison_support(dev)) {
dev->poison_val = le32_to_cpu(config.poison_val); diff --git
a/include/hw/boards.h b/include/hw/boards.h index
6fbbfd56c8..551b4b419e 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -296,6 +296,7 @@ struct MachineClass { typedef struct
DeviceMemoryState {
hwaddr base;
MemoryRegion mr;
+ ram_addr_t dimm_size;
} DeviceMemoryState;
/**
--
2.33.0