Re: [libvirt] [RFC PATCH 00/12] Add block write threshold event

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

not the node-name of the qcow2 protocol.

> - 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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