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

[Libaiqing]

Hi paolo,
     With -M pc,trim works well in windows guest with ide device and ahci bus.

     About the filter driver,you mean do something in windows virtio-scsi 
driver,let it send unmap command to qemu?

Thanks
baiqing.

> -----Original Message-----
> From: Paolo Bonzini [mailto:address@hidden
> Sent: Wednesday, July 24, 2013 2:46 PM
> To: Libaiqing
> Cc: address@hidden
> Subject: Re: trim in windows guest witch virtio
> 
> 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