motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-05 08:43:55 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

replay: introduce block devices record/replay

Browse source 
This patch introduces block driver that implement recording
and replaying of block devices' operations.
All block completion operations are added to the queue.
Queue is flushed at checkpoints and information about processed requests
is recorded to the log. In replay phase the queue is matched with
events read from the log. Therefore block devices requests are processed
deterministically.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
[ kwolf: Rebased onto modified and already applied part of the series ]
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Pavel Dovgalyuk 2016-03-14 10:45:10 +03:00 • committed by Kevin Wolf
parent 95b4aed5fd
commit 63785678f3
8 changed files with 209 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

20
docs/replay.txt
View file

@ -175,3 +175,23 @@ Sometimes the block layer uses asynchronous callbacks for its internal purposes
(like reading or writing VM snapshots or disk image cluster tables). In this
case bottom halves are not marked as "replayable" and do not saved
into the log.
Block devices
-------------
Block devices record/replay module intercepts calls of
bdrv coroutine functions at the top of block drivers stack.
To record and replay block operations the drive must be configured
as following:
-drive file=disk.qcow,if=none,id=img-direct
-drive driver=blkreplay,if=none,image=img-direct,id=img-blkreplay
-device ide-hd,drive=img-blkreplay
blkreplay driver should be inserted between disk image and virtual driver
controller. Therefore all disk requests may be recorded and replayed.
All block completion operations are added to the queue in the coroutines.
Queue is flushed at checkpoints and information about processed requests
is recorded to the log. In replay phase the queue is matched with
events read from the log. Therefore block devices requests are processed
deterministically.