NO_BUFFERING benchmarks

[adamsitnik]

Sample results:

Method	fileSize	count	Mean	Error	StdDev	Median	Min	Max	Allocated
ReadScatterAsync	1048576	4	8.566 ms	0.0462 ms	0.0432 ms	8.579 ms	8.496 ms	8.632 ms	24 KB
WriteGatherAsync	1048576	4	10.105 ms	0.8382 ms	0.9652 ms	9.922 ms	8.969 ms	12.288 ms	24 KB
ReadScatterAsync	1048576	16	3.506 ms	0.0501 ms	0.0444 ms	3.508 ms	3.446 ms	3.585 ms	13 KB
WriteGatherAsync	1048576	16	7.845 ms	0.7106 ms	0.8183 ms	7.782 ms	6.722 ms	9.594 ms	12 KB
ReadScatterAsync	104857600	4	494.695 ms	13.5187 ms	15.5682 ms	493.717 ms	465.158 ms	530.014 ms	2,353 KB
WriteGatherAsync	104857600	4	440.159 ms	16.8838 ms	18.7663 ms	441.222 ms	412.289 ms	480.287 ms	2,301 KB
ReadScatterAsync	104857600	16	188.437 ms	3.5286 ms	3.6236 ms	188.506 ms	182.998 ms	196.412 ms	1,189 KB
WriteGatherAsync	104857600	16	188.729 ms	32.4954 ms	37.4218 ms	171.521 ms	153.523 ms	279.160 ms	1,177 KB