Re: [Qemu-devel] trim in windows guest witch virtio

[Paolo Bonzini]

Il 24/07/2013 02:53, Libaiqing ha scritto:
> Hi paolo,
> 
>     I test window guest with ide device with the following config,trim with 
> ide drive failed.
> 
>      1 The host fs is ext4 with discard option: 
>        /dev/sdb1 on /home/sdb type ext4 (rw,relatime,discard,data=ordered)
>      
>      2 qemu config : ide drive with discard open
> x86_64-softmmu/qemu-system-x86_64 -enable-kvm -name win7 -M pc-0.15 -m 1024 
> -smp 2 -boot c -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2  -drive 
> file=/home/win7_base.qcow2,if=ide,index=0,format=qcow2,id=ad  -drive 
> file=/home/sdb/raw.img,if=ide,index=1,format=raw,id=hd,discard=on  -monitor 
> stdio   -vga qxl  -vnc :1 -device usb-tablet,id=input0

TRIM is supported only on "-M pc-1.5" and "-M pc".

>      3 In win7 guest,init drive d,fill it with files,then shift+del files
> 
>      4 The file /home/sdb/raw.img does not become small,when listing with -s 
> option.
> 
>      It seems that the windows ntfs does not send trim to ide controller. No 
> IDE_DMA_TRIM request received.

Note that this may not happen immediately.  NTFS may send TRIM later.

>      Is there any config wrong?
> 
>      Btw,I found the info from the URL: 
> http://msdn.microsoft.com/en-us/library/windows/desktop/hh848053(v=vs.85).aspx
>      Qemu can do the same thing like hyper-v with windows guest?

I don't know, I never tested it with Windows guests.  It looks like
Windows 8 would not need a filter driver to do TRIM on SCSI disks (you
could try with megasas, so that you do not need a driver for the HBA).

Paolo