* Get a fresh instance of executor for each benchmark invocation
And don't pre-initialize all of the executors at once, as this
might reach the maximum number of VMs limit in case we want to
test multiple Tart executors.
* Run benchmarks on Tart with different --root-disk-opts options
* Fix TestTart
* benchmark fio: introduce --prepare command-line argument
To be able to specify --prepare='sudo purge && sync', similarly to
Hyperfine[1].
[1]: https://github.com/sharkdp/hyperfine
* Benchmark Tart with --root-disk-opts=caching=cached separately too
* Add Ars Technica recommended benchmarks
* Tart executor: log SSH session standard output and standard error
* Reduce file I/O size from 16 to 10 GB to avoid "No space left on device"
* Remove random writing tests to make space for more read/read-write tests
* Add some "randrw"-style fio benchmarks
* Show latency in benchmark results
* Add sync benchmark and show read/write/sync latency
* README.md: add new benchmark results
Fedor Korotkov
Nikolay Edigaryev