[Xen-devel] RE: [Xen-changelog] [xen-unstable] blktap2: a completely rewritten blktap implementation

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

Just wondering... has this been tested with multiple domains
sharing the same blktap device?  (e.g. specifying
tap:aio:/pathto/file.img,hda,w! from two different domains
in a cluster)

> -----Original Message-----
> From: Xen patchbot-unstable
> [mailto:patchbot-unstable@xxxxxxxxxxxxxxxxxxx]
> Sent: Wednesday, May 27, 2009 5:31 AM
> To: xen-changelog@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-changelog] [xen-unstable] blktap2: a completely 
> rewritten
> blktap implementation
> 
> 
> # HG changeset patch
> # User Keir Fraser <keir.fraser@xxxxxxxxxx>
> # Date 1243335151 -3600
> # Node ID 1c627434605e7747689047e1761c193ceb4f9ef0
> # Parent  f210a633571c17c1a5e47980d53b00b0cab5b726
> blktap2: a completely rewritten blktap implementation
> 
> Benefits to blktap2 over the old version of blktap:
> 
> * Isolation from xenstore - Blktap devices are now created directly on
>    the linux dom0 command line, rather than being spawned in response
>    to XenStore events.  This is handy for debugging, makes blktap
>    generally easier to work with, and is a step toward a generic
>    user-level block device implementation that is not Xen-specific.
> 
> * Improved tapdisk infrastructure: simpler request forwarding, new
>    request scheduler, request merging, more efficient use of AIO.
> 
> * Improved tapdisk error handling and memory management.  No
>    allocations on the block data path, IO retry logic to protect
>    guests
>    transient block device failures.  This has been tested and is known
>    to work on weird environments such as NFS soft mounts.
> 
> * Pause and snapshot of live virtual disks (see xmsnap script).
> 
> * VHD support.  The VHD code in this release has been rigorously
>    tested, and represents a very mature implementation of the VHD
>    image
>    format.
> 
> * No more duplication of mechanism with blkback.  The blktap kernel
>    module has changed dramatically from the original blktap.  Blkback
>    is now always used to talk to Xen guests, blktap just presents a
>    Linux gendisk that blkback can export.  This is done while
>    preserving the zero-copy data path from domU to physical device.
> 
> These patches deprecate the old blktap code, which can hopefully be
> removed from the tree completely at some point in the future.
> 
> Signed-off-by: Jake Wires <jake.wires@xxxxxxxxxx>
> Signed-off-by: Dutch Meyer <dmeyer@xxxxxxxxx>

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel