Bug 819485
| Summary: | [NFR] libvirt: Returning the watermark for all the images opened for writing | |||
|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Federico Simoncelli <fsimonce> | |
| Component: | libvirt | Assignee: | Eric Blake <eblake> | |
| Status: | CLOSED DEFERRED | QA Contact: | Virtualization Bugs <virt-bugs> | |
| Severity: | unspecified | Docs Contact: | ||
| Priority: | unspecified | |||
| Version: | 6.3 | CC: | abaron, acathrow, alitke, bsarathy, cwei, dallan, dyuan, eblake, jcody, juzhang, mkenneth, mzhan, pbonzini, tburke | |
| Target Milestone: | rc | |||
| Target Release: | --- | |||
| Hardware: | Unspecified | |||
| OS: | Unspecified | |||
| Whiteboard: | ||||
| Fixed In Version: | Doc Type: | Bug Fix | ||
| Doc Text: | Story Points: | --- | ||
| Clone Of: | ||||
| : | 822165 1041569 (view as bug list) | Environment: | ||
| Last Closed: | 2013-12-12 17:39:45 UTC | Type: | Bug | |
| Regression: | --- | Mount Type: | --- | |
| Documentation: | --- | CRM: | ||
| Verified Versions: | Category: | --- | ||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | ||
| Cloudforms Team: | --- | Target Upstream Version: | ||
| Embargoed: | ||||
| Bug Depends On: | 822165, 1041564 | |||
| Bug Blocks: | 1041569, 1158094 | |||
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Description
Federico Simoncelli
2012-05-07 11:39:58 UTC
> The preferred way to fetch the watermark is with the current blockstats
> (wr_highest_offset) and the qemu-kvm process should return the highest offset
> between the source image and the destination image.
This could be done by libvirt. qemu-kvm would return the value in info block-job.
(In reply to comment #2) > > The preferred way to fetch the watermark is with the current blockstats > > (wr_highest_offset) and the qemu-kvm process should return the highest offset > > between the source image and the destination image. > > This could be done by libvirt. qemu-kvm would return the value in info > block-job. Eric what do you think? If I understand correctly, you are proposing new output in 'query-block-jobs', and requesting that libvirt expose this new information via virDomainBlockJobInfo(). Alas, virDomainBlockJobInfoPtr is a poorly-designed API - it has a fixed-size struct, so there is no way to directly cram any additional information into the RPC call currently used for virDomainBlockJobInfo(). That said, at least it has a flags parameter; I could do a hack where the use of a non-zero flags says to reuse existing members of the struct for different statistics (that is, instead of reporting cur/end, we could say that the use of a flag reports the watermark stat instead). Another possibility is to use virDomainBlockStatsFlags(), which is a properly-designed API flexible enough to add new parameters. It would be feasible to define new block stats corresponding to any information associated with a block job, where the stat is normally 0 but during a block job can be queried from the job. So, if the question is whether we can support this using just the RHEL 6.3 API, I think the answer is yes. But we also have to consider that this is very late in the RHEL 6.3 cycle; how badly do you need the information and by when? This request was not resolved in time for the current release. Red Hat invites you to ask your support representative to propose this request, if still desired, for consideration in the next release of Red Hat Enterprise Linux. The dependent bug 822165 is flagged for 6.5, so I'm moving this bug too. But the feature overall was superseded by bug 844627, so it could even be WONTFIX. Updating the title according to: https://bugzilla.redhat.com/show_bug.cgi?id=822165#c8 Discussed this with Andrew Cathrow: we're targeting this feature at RHEL7.x, so closing this as WONTFIX in RHEL6. Clone for RHEL7 is Bug 1041569 |