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[Qemu-devel] [v1 Patch 0/10]Qemu: Dynamic host pagecache change and imag
[Qemu-devel] [v1 Patch 0/10]Qemu: Dynamic host pagecache change and image file reopen
Sat, 16 Jun 2012 02:16:48 +0530
For changing host pagecache setting of a running VM, it is
important to have a safe way of reopening its image file.
Following patchset introduces:
* a generic way to reopen image files safely.
In this approach, before reopening an image, for each
block driver, its state will be stashed. Incase preparation,
(bdrv_reopen_prepare) for reopening returns success, the stashed
state will be cleared (bdrv_reopen_commit) and reopened state will
be used further. Incase preparation of reopening returns failure,
the state of the driver will be rolled back (bdrv_reopen_abort)
to the stashed state. This approach is implemented for raw-posix,
raw-win32, vmdk, qcow, qcow2 and qed block drivers.
* qmp and hmp command 'block_set_hostcache' using which host
pagecache setting for a block device can be changed
when the VM is running.
* BDRVReopenState, a generic structure which can be
extended by each of the block drivers to reopen
respective image files.
* Currently driver state is stashed by field-by-field copy.
Optimise this by stashing only the required fields.
* Find out other drivers needing bdrv_reopen implementation.
* Do some more extensive testing, especially with drivers like
floppy, cdrom etc..
Earlier discussions on RFC for dynamic change of host pagecache can be
found at: http://lists.gnu.org/archive/html/qemu-devel/2012-01/msg04139.html
New block command added:
-- Sets hostcache parameter for block device while guest is running.
block_set_hostcache <device> <option>
<device> = block device
<option> = on/off
qemu/block.c | 127 ++++++++++++++++++++++++++++++++--
qemu/block.h | 5 +
qemu/block/qcow.c | 108 +++++++++++++++++++++++++++++
qemu/block/qcow2.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++++
qemu/block/qed.c | 103 ++++++++++++++++++++++++++++
qemu/block/raw-posix.c | 123 ++++++++++++++++++++++++++++++++++
qemu/block/raw-win32.c | 96 ++++++++++++++++++++++++++
qemu/block/raw.c | 20 +++++
qemu/block/vmdk.c | 103 ++++++++++++++++++++++++++++
qemu/block_int.h | 11 +++
qemu/blockdev.c | 24 ++++++
qemu/hmp-commands.hx | 16 ++++
qemu/hmp.c | 11 ++
qemu/hmp.h | 1
qemu/qapi-schema.json | 20 ++++-
qemu/qemu-common.h | 1
qemu/qerror.c | 8 ++
qemu/qerror.h | 6 +
qemu/qmp-commands.hx | 24 ++++++
19 files changed, 971 insertions(+), 13 deletions(-)
- [Qemu-devel] [v1 Patch 0/10]Qemu: Dynamic host pagecache change and image file reopen,
Supriya Kannery <=
- [Qemu-devel] [v1 Patch 1/10]Qemu: Enhance "info block" to display host cache setting, Supriya Kannery, 2012/06/15
- [Qemu-devel] [v1 Patch 3/10]Qemu: Cmd "block_set_hostcache" for dynamic cache change, Supriya Kannery, 2012/06/15
- [Qemu-devel] [v1 Patch 4/10]Qemu: Framework for reopening image files safely, Supriya Kannery, 2012/06/15
- [Qemu-devel] [v1 Patch 2/10]Qemu: Error classes for hostcache setting and data sync failures, Supriya Kannery, 2012/06/15
- [Qemu-devel] [v1 Patch 6/10]Qemu: raw-win32 image file reopen, Supriya Kannery, 2012/06/15
- [Qemu-devel] [v1 Patch 5/10]Qemu: raw-posix image file reopen, Supriya Kannery, 2012/06/15