qcow2 performance roadmap
- What can be done to achieve near-raw image format performance?
- some discussion points from Kevin on list
http://lists.nongnu.org/archive/html/qemu-devel/2010-11/msg02126.html
- please follow up on the list
- some perf numbers (latest upstream qcow2 compared with qed)
- qed is fully async, added unconditional flush to model qcow2
- http://wiki.qemu.org/Qcow2/PerformanceRoadmap
- qcow2 not scaling as well
- metadata handling still quite sync
- sequential reads not scaling at all (a
- only serialization point is two accesses to same block and need to
allocate
- template based backing file is common (esp. in cloud)
- perf data suggests that data/table format dictates performance ceiling
- barriers off on underlying fs, cache=writethrough
- raw backing file (sparse) grows with basic tools like cp
- suggestion: qed == qcow2 v3
- wouldn't support encryption and compression (Kevin won't do this)
usb-ccid
- concern about external library implementation
- hard to add device features, enhancements, live migration protocol changes
- external library
- will resend patch to
vcpu hard limits
- will continue discussion on list
0.14 (release date, bug day, -rc planning, etc)
- aiming for dec 15th
- will send note out after call with release schedule
0.13.x
- will connect with jforbes regarding -stable maintainance
gPXE vs. iPXE
- ipxe is new fork
- ipxe looking more active (including original gpxe developers)
- which is a better choice?
- iPXE more active, gPXE stalled
- some concern about where the community sits (gPXE has irc, bug
reports, etc)
- some concern about boot delay with iPXE
- qemu not updating roms that frequently, next time we need to update,
can evaluate
- syslinux still using gPXE
