On Thu, Feb 23, 2017 at 13:50:03 -0600, Eric Blake wrote:
On 02/23/2017 01:21 PM, Peter Krempa wrote:
Since I'm a procrastinator and I wanted to do this after full node-name support is added I'm kind of late for this release here. Since oVirt is asking for this feature for a very long time I would like to deliver it ASAP though.
Thanks for picking up on this. I tried once a long time ago: https://www.redhat.com/archives/libvir-list/2015-June/msg01111.html
and got stalled on node name weirdness, so it never went in.
This series adds a event which is fired once a guest writes beyond a configured offset in the backing file. The threshold offset is configurable via a new API.
This series is in RFC state since I did not manage to polish few details mostly connected to node names:
- currently only the top level image can be selected - some blockjobs may clear the remembered node names and thus break this ( re-detection of the backing chain needs to be connected with node name detection ) - the node name detection code is VERY crude
Indeed, that's where I got stalled, but I think you may already be further along than my attempt. (It may also be that the QMP side from qemu is easier to use now than when I first tried)
- I'm not sure how well it plays with qcow images, since I select only the top level node (qcow protocol) rather than the file backing it
That may be a deal-breaker - my recollection is that you HAVE to use the node-name of the file backing the qcow2 to get the useful threshold, and
Yes, that's what I expect as well.
not the node-name of the qcow2 protocol.
For -blockdev support we will need full node-name detection anyways. I plan to keep two node-names per virStorageSource, one that describes the format layer and one that describes the protocol/backing layer. The last patch is just a very dirty hack to see that the rest was wired up properly.
- the documentation probably sucks since I did not proof-read
Any feedback is welcome.
Peter Krempa (12): util: storage: Split out useful bits of virStorageFileParseChainIndex util: storage: Add preliminary storage for node names into virStorageSource lib: Introduce event for tracking disk backing file write threshold qemu: monitor: Add support for BLOCK_WRITE_THRESHOLD event qemu: domain: Add helper to lookup disk by node name qemu: domain: Add helper to generate indexed backing store names qemu: process: Wire up firing of the VIR_DOMAIN_EVENT_ID_BLOCK_THRESHOLD event lib: Add API for setting the threshold size for VIR_DOMAIN_EVENT_ID_BLOCK_THRESHOLD virsh: Implement 'blockthreshold' command to call virDomainSetBlockThreshold qemu: domain: Add helper to look up disk soruce by the backing store string qemu: implement qemuDomainSetBlockThreshold qemu: WIP: lookup nodenames
-- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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