[Qemu-devel] Questions about Block subsystem in QEMU.

[Qemu-devel] Questions about Block subsystem in QEMU.

[Yaodong Yang]

[-- Attachment #1: Type: text/plain, Size: 343 bytes --]

hello everyone,

I have a question about the qemu block-subsytem. When a user in guest os
perform an io operation, how this io request performed in the qemu. Where
is the start point in qemu code to serve this request.

Thanks!

-- 
Yaodong Yang
Computer Science and Engineering Department
University of Nebraska--Lincoln,
Lincoln, NE, U.S.A.

[-- Attachment #2: Type: text/html, Size: 479 bytes --]

Re: [Qemu-devel] Questions about Block subsystem in QEMU.

[Stefan Hajnoczi]

On Mon, Jul 08, 2013 at 11:15:12PM -0500, Yaodong Yang wrote:
> I have a question about the qemu block-subsytem. When a user in guest os
> perform an io operation, how this io request performed in the qemu. Where
> is the start point in qemu code to serve this request.

QEMU emulates a number of different storage controllers, including
virtio-blk, virtio-scsi, IDE, USB Mass Storage Device, SD cards, etc.

See hw/block/ for storage controller emulation code, which the guest
drivers invoke through hardware register accesses.

Stefan

[Qemu-devel] The difference between qemu-kvm-1.2.0 & qemu-1.5.1

[Yaodong Yang]

[-- Attachment #1: Type: text/plain, Size: 694 bytes --]

Hi everyone,

Previously, I used the qemu-kvm-1.2.0 from (http://www.linux-kvm.org/page/Downloads), and it worked well in my ubuntu server. Later, I found that some of the implementation(qemu-kvm-1.2.0) is out of date, so that I changed to qemu-1.5.1 (http://wiki.qemu.org/Download). I found that installing a guest ubuntu vm (qcow2 backup images) in qemu-1.5.1 is much slower than that in qemu-kvm-1.2.0. 

So could someone tell me the differences between them? particularly why the qemu-1.5.1 is slower than the qemu-kvm-1.2.0.  

I would like to implement something in the io path. My platform is a x86 64bit server, and my host os is ubuntu 12.04 desktop, 64 bits.

Thanks!
Yaodong

[-- Attachment #2: Type: text/html, Size: 1022 bytes --]

Re: [Qemu-devel] [Qemu-discuss] The difference between qemu-kvm-1.2.0 & qemu-1.5.1

[Fam Zheng]

On Mon, 07/22 13:51, Yaodong Yang wrote:
> Hi everyone,
> 
> Previously, I used the qemu-kvm-1.2.0 from (http://www.linux-kvm.org/page/Downloads), and it worked well in my ubuntu server. Later, I found that some of the implementation(qemu-kvm-1.2.0) is out of date, so that I changed to qemu-1.5.1 (http://wiki.qemu.org/Download). I found that installing a guest ubuntu vm (qcow2 backup images) in qemu-1.5.1 is much slower than that in qemu-kvm-1.2.0. 
> 
> So could someone tell me the differences between them? particularly why the qemu-1.5.1 is slower than the qemu-kvm-1.2.0.  
> 
> I would like to implement something in the io path. My platform is a x86 64bit server, and my host os is ubuntu 12.04 desktop, 64 bits.
> 

Are you using KVM? If not, please use --enable-kvm to compile QEMU with
kvm support and run with '-enable-kvm'.

What's your command to run it?

-- 
Fam