Messages in this thread | | | Subject | Re: [PATCH v3 4/4] xen-blkback: support dynamic unbind/bind | From | Jürgen Groß <> | Date | Thu, 12 Dec 2019 07:07:06 +0100 |
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On 11.12.19 16:29, Paul Durrant wrote: > By simply re-attaching to shared rings during connect_ring() rather than > assuming they are freshly allocated (i.e assuming the counters are zero) > it is possible for vbd instances to be unbound and re-bound from and to > (respectively) a running guest. > > This has been tested by running: > > while true; > do fio --name=randwrite --ioengine=libaio --iodepth=16 \ > --rw=randwrite --bs=4k --direct=1 --size=1G --verify=crc32; > done > > in a PV guest whilst running: > > while true; > do echo vbd-$DOMID-$VBD >unbind; > echo unbound; > sleep 5; > echo vbd-$DOMID-$VBD >bind; > echo bound; > sleep 3; > done > > in dom0 from /sys/bus/xen-backend/drivers/vbd to continuously unbind and > re-bind its system disk image. > > This is a highly useful feature for a backend module as it allows it to be > unloaded and re-loaded (i.e. updated) without requiring domUs to be halted. > This was also tested by running: > > while true; > do echo vbd-$DOMID-$VBD >unbind; > echo unbound; > sleep 5; > rmmod xen-blkback; > echo unloaded; > sleep 1; > modprobe xen-blkback; > echo bound; > cd $(pwd); > sleep 3; > done > > in dom0 whilst running the same loop as above in the (single) PV guest. > > Some (less stressful) testing has also been done using a Windows HVM guest > with the latest 9.0 PV drivers installed. > > Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Juergen
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