[Libguestfs] [PATCH nbdkit NOT WORKING 0/2] vddk: Relax threading model.

[Richard W.M. Jones]

I believe this roughly implements Nir's proposal here:

https://www.redhat.com/archives/libguestfs/2020-August/msg00028.html

Unfortunately it doesn't work for me.  It actually slows things down
quite a lot, for reasons I don't understand.  Note the adjustment of
the pool-max parameter and how it affects the total time.  The results
are quite reproducible.

$ ./nbdkit -r -U - vddk libdir=~/tmp/vddk-7.0.0/vmware-vix-disklib-distrib user=root password=*** server=*** thumbprint=*** vm=moref=3 file='[datastore1] Fedora 28/Fedora 28.vmdk' pool-max=1 --run 'time qemu-img convert -p -W -m 16 $nbd /var/tmp/out' 
    (100.00/100%)

real	1m8.031s
user	0m0.112s
sys	0m1.560s

$ ./nbdkit -r -U - vddk libdir=~/tmp/vddk-7.0.0/vmware-vix-disklib-distrib user=root password=*** server=*** thumbprint=*** vm=moref=3 file='[datastore1] Fedora 28/Fedora 28.vmdk' pool-max=8 --run 'time qemu-img convert -p -W -m 16 $nbd /var/tmp/out' 
    (100.00/100%)

real	1m27.790s
user	0m0.099s
sys	0m1.625s

I'm still investigating this.  Could be a simple coding error somewhere.

Rich.