Re: [libvirt] RFC (V2) New virDomainBlockPull API family to libvirt

Thanks Daniel.  The upstream code is looking good.  I will work on adding some documentation to the development guide. On 07/22/2011 01:07 AM, Daniel Veillard wrote: > On Thu, Jul 21, 2011 at 01:55:04PM -0500, Adam Litke wrote: >> Here are the patches to implement the BlockPull/BlockJob API as discussed and >> agreed to.  I am testing with a python script (included for completeness as the >> final patch).  The qemu monitor interface is not expected to change in the >> future.  Stefan is planning to submit placeholder commands for upstream qemu >> until the generic streaming support is implemented. >> >> Changes since V1: >>  - Make virDomainBlockPullAbort() and virDomainGetBlockPullInfo() into a >>    generic BlockJob interface. >>  - Added virDomainBlockJobSetSpeed() >>  - Rename VIR_DOMAIN_EVENT_ID_BLOCK_PULL event to fit into block job API >>  - Add bandwidth argument to virDomainBlockPull() >> >> Summary of changes since first generation patch series: >>  - Qemu dropped incremental streaming so remove libvirt incremental >>    BlockPull() API >>  - Rename virDomainBlockPullAll() to virDomainBlockPull() >>  - Changes required to qemu monitor handlers for changed command names >> >> -- >> >> To help speed the provisioning process for large domains, new QED disks are >> created with backing to a template image.  These disks are configured with >> copy on read such that blocks that are read from the backing file are copied >> to the new disk.  This reduces I/O over a potentially costly path to the >> backing image. >> >> In such a configuration, there is a desire to remove the dependency on the >> backing image as the domain runs.  To accomplish this, qemu will provide an >> interface to perform sequential copy on read operations during normal VM >> operation.  Once all data has been copied, the disk image's link to the >> backing file is removed. >> >> The virDomainBlockPull API family brings this functionality to libvirt. >> >> virDomainBlockPull() instructs the hypervisor to stream the entire device in >> the background.  Progress of this operation can be checked with the function >> virDomainBlockJobInfo().  An ongoing stream can be cancelled with >> virDomainBlockJobAbort().  virDomainBlockJobSetSpeed() allows you to limit the >> bandwidth that the operation may consume. >> >> An event (VIR_DOMAIN_EVENT_ID_BLOCK_JOB) will be emitted when a disk has been >> fully populated or if a BlockPull() operation was terminated due to an error. >> This event is useful to avoid polling on virDomainBlockJobInfo() for >> completion and could also be used by the security driver to revoke access to >> the backing file when it is no longer needed. > >   Thanks Adam for that revised patch set. > >     ACK > > It all looked good to me, based on previous review and a last look. > I just had to fix a few merge conflicts due to new entry points being > added in the meantime and one commit message, but basically it was clean :-) > >   So I pushed the set except 8 of course. I'm not sure if we should try > to store it in the example, or on the wiki. The Wiki might be a bit more > logical because I'm not sure we can run the test as is now in all > setups. > > >   I think the remaining item would be to add documentation about how to > use this, the paragraphs above should probably land somewhere on the web > site, ideally on the development guide >   http://libvirt.org/devguide.html > but I'm open to suggestions :-) > > Daniel > -- Adam Litke IBM Linux Technology Center -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list