[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [QEMU PATCH 0/2] virtio-blk: writeback cache enable imp
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [QEMU PATCH 0/2] virtio-blk: writeback cache enable improvements |
Date: |
Wed, 01 Aug 2012 17:52:32 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 |
Il 23/07/2012 18:32, Paolo Bonzini ha scritto:
> Il 03/07/2012 15:20, Paolo Bonzini ha scritto:
>> > 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
> Ping - Anthony, mst?
Ping^2, so we can switch writethrough->writeback in 1.2.
Paolo
- Re: [Qemu-devel] [QEMU PATCH 0/2] virtio-blk: writeback cache enable improvements,
Paolo Bonzini <=