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[Qemu-devel] [QEMU PATCH 0/2] virtio-blk: writeback cache enable improve
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [QEMU PATCH 0/2] virtio-blk: writeback cache enable improvements |
Date: |
Tue, 3 Jul 2012 15:20:40 +0200 |
These patches let virtio-blk use the new support for toggling the cache
mode between writethrough and writeback.
The first patch introduces a new feature bit and configuration field to
do this. The second patch disables writeback caching for guests that do
not negotiate VIRTIO_BLK_F_WCACHE (meaning that they cannot send flush
requests), so that limited or older guests are now safe wrt power losses.
VIRTIO_BLK_F_FLUSH has been introduced in Linux 2.6.32 (in 2009) and was
backported to RHEL/CentOS 5.6 (in 2010).
The Windows drivers (which work by emulating SCSI on top of virtio-blk)
have bugs in this area, which I reported on the Red Hat Bugzilla as
bugs 837321 and 837324. With these patches they will suffer a
performance hit but gain correctness.
Paolo Bonzini (2):
virtio-blk: support VIRTIO_BLK_F_CONFIG_WCE
virtio-blk: disable write cache if not negotiated
hw/virtio-blk.c | 30 ++++++++++++++++++++++++++++--
hw/virtio-blk.h | 4 +++-
2 files changed, 31 insertions(+), 3 deletions(-)
--
1.7.10.2
- [Qemu-devel] [QEMU PATCH 0/2] virtio-blk: writeback cache enable improvements,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 1/2] virtio-blk: support VIRTIO_BLK_F_CONFIG_WCE, Paolo Bonzini, 2012/07/03
- [Qemu-devel] [PATCH 2/2] virtio-blk: disable write cache if not negotiated, Paolo Bonzini, 2012/07/03
- Re: [Qemu-devel] [PATCH 2/2] virtio-blk: disable write cache if not negotiated, Kevin Wolf, 2012/07/03
- Re: [Qemu-devel] [PATCH 2/2] virtio-blk: disable write cache if not negotiated, Paolo Bonzini, 2012/07/03
- Re: [Qemu-devel] [PATCH 2/2] virtio-blk: disable write cache if not negotiated, Kevin Wolf, 2012/07/04
- Re: [Qemu-devel] [PATCH 2/2] virtio-blk: disable write cache if not negotiated, Paolo Bonzini, 2012/07/04
- Re: [Qemu-devel] [PATCH 2/2] virtio-blk: disable write cache if not negotiated, Kevin Wolf, 2012/07/04
- Re: [Qemu-devel] [PATCH 2/2] virtio-blk: disable write cache if not negotiated, Paolo Bonzini, 2012/07/04