Re: [Qemu-devel] GSoC: Improved image format compatibility

[Lyu Mitnick]

Hello

I have some question about asynchronous i/o in QEMU block driver: Why a file

format with asynchronous i/o support(ex. qcow) doesn't need to register 

bdrv_read/bdrv_write which is registered in vhd file format?? Would qcow block driver

also support synchronous i/o??

thanks a lot

Mitnick

2011/4/2 Kevin Wolf <address@hidden>

Am 01.04.2011 17:15, schrieb Lyu Mitnick:

> Hello Stefan
>
>     Hello Mitnick,
>
>     asynchronous i/o is also missing in block/vpc.c.
>
>     All newer block drivers support asynchronous reads and writes,
>     only some old drivers don't.
>
>     So adding asynchronous i/o to at least some of the old drivers
>     would improve their usability.
>
>     Look for "aio" in block/*.c to get a starting point.
>
>     Regards
>     Stefan (W.)
>
>
> I look for "aio" in block/*.c as a starting point of asynchronous i/o.
> And I
> found that there isn't any "aio" keywords in block/vmdk.c. block/vmdk.c
> is used as block driver for the VMDK format. Is it means that asynchronous
> i/o is also missing in VMDK format?

Yes, the VMDK implementation is completely synchronous.

Kevin