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Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd
From: |
Richard W.M. Jones |
Subject: |
Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd |
Date: |
Tue, 7 Jan 2014 21:22:10 +0000 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
On Tue, Jan 07, 2014 at 09:48:17PM +0100, Paolo Bonzini wrote:
> Il 07/01/2014 21:27, Richard W.M. Jones ha scritto:
> > Not much more what I said in the original email (especially see the
> > attached script which you can download from the bottom of this page:
> > https://lists.gnu.org/archive/html/qemu-devel/2014-01/msg00084.html )
> >
> > Basically it tries to dd /dev/zero into the virtio-scsi device exposed
> > by qemu, then calls sg_unmap (there are two devices, it only unmaps
> > the first so we can hopefully see the difference), but it doesn't seem
> > to have any effect on the underlying file. The underlying file is a
> > regular raw-format file on ext4.
> >
> > I called sg_readcap/sg_vpd and we seem to have all the right
> > capability bits exposed.
> >
> > This script won't work with regular libguestfs. I compiled a special
> > appliance that had the sg tools included.
>
> Try again with the pull request of
> http://permalink.gmane.org/gmane.comp.emulators.qemu/248421
No difference from before, as far as I can see.
Here is the output of sparsetest.sh:
0 /tmp/test1
0 /tmp/test2
Read Capacity results:
Protection: prot_en=0, p_type=0, p_i_exponent=0
Logical block provisioning: lbpme=1, lbprz=0
Last logical block address=204799 (0x31fff), Number of logical blocks=204800
Logical block length=512 bytes
Logical blocks per physical block exponent=0
Lowest aligned logical block address=0
Hence:
Device size: 104857600 bytes, 100.0 MiB, 0.10 GB
Block limits VPD page (SBC):
Write same no zero (WSNZ): 1
Maximum compare and write length: 0 blocks
Optimal transfer length granularity: 0 blocks
Maximum transfer length: 0 blocks
Optimal transfer length: 0 blocks
Maximum prefetch length: 0 blocks
Maximum unmap LBA count: 2097152
Maximum unmap block descriptor count: 255
Optimal unmap granularity: 8
Unmap granularity alignment valid: 0
Unmap granularity alignment: 0
Maximum write same length: 0x0 blocks
16M /tmp/test1 <--- note both file disk
16M /tmp/test2 <--- usages are the same
Those are raw files on ext4. I'll try qcow2 and follow up.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into KVM guests.
http://libguestfs.org/virt-v2v
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/02
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/07
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/07
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/07
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/07
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd,
Richard W.M. Jones <=
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/08
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/08
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/08
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Richard W.M. Jones, 2014/01/08
- Re: [Qemu-devel] TRIM/DISCARD/UNMAP support on qemu-nbd, Paolo Bonzini, 2014/01/09