Xen Roadmap 11 09

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Xen.org community presentation from Xen Summit Asia 2009

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Xen Roadmap 11 09

  1. 1. ® Xen Hypervisor Update Keir Fraser, Citrix Systems Inc. 11/26/2009 1
  2. 2. ® Release plans • Current stable release: 3.4.2 – Released just last week • Next releases: 3.4.3 and 4.0.0 – Both anticipated early in the New Year • Ongoing strategy: – Maintain two stable branches until the later one has matured enough for switchover – Quarterly releases from stable branches – Six to nine months between major releases 11/26/2009 2
  3. 3. ® Linux kernel: pv_ops • Efficient support has been upstream for a couple of years now – Running well as ‘domU’ VM • Jeremy Fitzhardinge manages the tree for further development – Path for further upstreaming to kernel.org – Default kernel for Xen 4.0 • Still to do: – Port your favourite backend driver – Test! 3
  4. 4. ® Virtual block devices: blktap2 • Support VHD storage format • Snapshot virtual disks – Checkpointing, gold images, … • Simplified kernel support – Leverage blkback • Simpler invocation model – Command-line driven rather than xenstore – More generic, easier test and debug 4
  5. 5. ® High availability: Remus • Maintain an up-to-date replica of a VM on a backup server – Regular (50ms) checkpoints – Buffer I/O over this interval (IMQ, blktap2) • Fail over to backup if primary fails – Simple heartbeat protocol – But scope for using more featureful external monitors such as Linux-HA • Simple and transparent 5
  6. 6. ® Network performance: netchannel2 • Network virtualisation is particularly hard – High packet rates; latency sensitive • Old netfront/back drivers have limitations – High cost for packet receive – Not designed for next-generation NICs • Ongoing work on netchannel2 to address this • Lazy copy in the guest (reduces dom0 load) – Provide guest a copy-only, sub-page, revocable grant • Support multi-queue NICs – DMA directly to guest buffers • Smart NICs, SR-IOV • Reusable extensible ring architecture 11/26/2009 6
  7. 7. ® Page sharing • Potential for reducing memory pressure by sharing identical pages across VMs – Significant savings in ‘ideal’ cases – Rather smaller gains in typical heterogeneous scenarios (10-20%) • How to find identical pages? – Identical disc blocks • Allows memory overcommit – Hence requires demand paging – Or don’t give spare pages directly back to guests 11/26/2009 7
  8. 8. ® Toolstack consolidation: libxenlight • A range of toolstacks now in use – Xend, xapi, xenvm • Share common code at the lowest level – Libxenctrl, libxenguest • But still a good deal of shareable infrastructure is implemented separately in each toolstack • Libxenlight: higher-level operations which can be shared among all toolstacks – Implemented in C, licensed under LGPL – Domain creation, destruction, migration, PCI passthru, … • Plans to move all toolstacks over to this library (and delete equivalent but non-shared code) 11/26/2009 8
  9. 9. ® Managing development • Use the developer mailing lists – xen-devel@lists.xensource.com – {xci-devel,xen-api}@lists.xensource.com – Requests for comments – Announcements of dev plans – Patches posted for comment, review and checkin • Use the wiki – http://wiki.xensource.com/xenwiki/XenRoadMap 9

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