Re: Reply: [PATCH] virtio-balloon: optimize the virtio-balloon on the ARM platform.

[David Hildenbrand <david@redhat.com>]

> 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 approximately 60%
> efficiency of balloon process on the ARM platform.
> 
> We tested the total amount of time required for the balloon inflation process on ARM:
> inflate the balloon to 64GB of a 128GB guest under stress.
> Before: 102 seconds
> After: 42 seconds
> 
> Signed-off-by: Qi Xi <xiqi2@huawei.com>
> Signed-off-by: Ming Yang yangming73@huawei.com
> ---
>   hw/mem/pc-dimm.c           |  2 ++
>   hw/virtio/virtio-balloon.c | 33 +++++----------------------------
>   include/hw/boards.h        |  1 +
>   3 files changed, 8 insertions(+), 28 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;
>   }

Ahh, missed that my previous comment was not addressed: we only want to 
track "real" DIMMs, not NVDIMMs.

-- 
Thanks,

David / dhildenb