On 12/06/14 09:14, Eric Blake wrote: > Wire up backing chain recursion. Note that for now, we just use > the same allocation numbers for read-only backing files as what > offline domains would report. It is not the correct allocation > number for qcow2 over block devices during block-commit, and it > misses out on the fact that qemu also reports read statistics on > backing files that are worth knowing about (seriously - for a > thin-provisioned setup, it would be nice to easily get at a count > of how many reads were serviced from the backing file in relation > to reads serviced by the active layer). But it is at least > sufficient to prove that the algorithm is working, and to let > other people start coding to the interface while waiting for > later patches that get the correct information. Is that a proof-of-concept then? I'd like to avoid adding stats fields that will change, especially this close to the release as we're running into the risk of baking it in. > > For a running domain, where one of the two images has a backing > file, I see the traditional output: > > $ virsh domstats --block testvm2 > Domain: 'testvm2' > block.count=2 > block.0.name=vda > block.0.path=/tmp/wrapper.qcow2 > block.0.rd.reqs=1 > block.0.rd.bytes=512 > block.0.rd.times=28858 > block.0.wr.reqs=0 > block.0.wr.bytes=0 > block.0.wr.times=0 > block.0.fl.reqs=0 > block.0.fl.times=0 > block.0.allocation=0 > block.0.capacity=1310720000 > block.0.physical=200704 > block.1.name=vdb > block.1.path=/dev/sda7 > block.1.rd.reqs=0 > block.1.rd.bytes=0 > block.1.rd.times=0 > block.1.wr.reqs=0 > block.1.wr.bytes=0 > block.1.wr.times=0 > block.1.fl.reqs=0 > block.1.fl.times=0 > block.1.allocation=0 > block.1.capacity=1310720000 > > vs. the new output: > > $ virsh domstats --block --backing testvm2 > Domain: 'testvm2' > block.count=3 > block.0.name=vda > block.0.path=/tmp/wrapper.qcow2 > block.0.rd.reqs=1 > block.0.rd.bytes=512 > block.0.rd.times=28858 > block.0.wr.reqs=0 > block.0.wr.bytes=0 > block.0.wr.times=0 > block.0.fl.reqs=0 > block.0.fl.times=0 > block.0.allocation=0 > block.0.capacity=1310720000 > block.0.physical=200704 > block.1.name=vda > block.1.path=/dev/sda6 > block.1.backingIndex=1 > block.1.allocation=1073741824 > block.1.capacity=1310720000 > block.1.physical=1073741824 > block.2.name=vdb > block.2.path=/dev/sda7 > block.2.rd.reqs=0 > block.2.rd.bytes=0 > block.2.rd.times=0 > block.2.wr.reqs=0 > block.2.wr.bytes=0 > block.2.wr.times=0 > block.2.fl.reqs=0 > block.2.fl.times=0 > block.2.allocation=0 > block.2.capacity=1310720000 ACK to the idea of the stat output idea ... > > * src/qemu/qemu_driver.c (QEMU_DOMAIN_STATS_BACKING): New internal > enum bit. > (qemuConnectGetAllDomainStats): Recognize new user flag, and pass > details to... > (qemuDomainGetStatsBlock): ...here, where we can do longer recursion. > (qemuDomainGetStatsOneBlock): Output new field. > > Signed-off-by: Eric Blake <eblake@xxxxxxxxxx> > --- > src/qemu/qemu_driver.c | 55 +++++++++++++++++++++++++++++++++++++++++--------- > 1 file changed, 46 insertions(+), 9 deletions(-) > .. but we shouldn't add code that reports wrong data. Peter
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