[Libguestfs] [PATCH libnbd 0/2] copy: Set default request-size to 2**18 (262144 bytes)

[Richard W.M. Jones]

As Nir has pointed out, our current default for nbdcopy --request-size
is far from optimal.  In this patch series I have changed the default
to something which is better, and provided some benchmark results.

With this simplistic approach it's not possible to choose a default
which is best in all situations.  That will likely require us to
benchmark many machines and try to work out a formula relating
measurable aspects of those machines like L3 cache size to the best
request size, but that's a lot more work.

Also one of the tests implicitly depended on the default size so I had
to adjust the test.

Rich.