The author defined fair in a pretty industry standard way:
> One user should not be able to block another's work.
A multi-tenant architecture implies over committing resources to achieve better economics. Once upon a time, decades ago, when computers were so expense that companies payed for batch processing instead of owning their own, FIFO was acceptable. (And for a tiny part of the market it still is.) But ever since the rise of time-sharing operating systems, users have come to expect short delays for small tasks. If you let one customer monopolize your capacity because they submitted a mountain of work before a second customer submits a handful, you probably won't have the second customer much longer.
> One user should not be able to block another's work.
A multi-tenant architecture implies over committing resources to achieve better economics. Once upon a time, decades ago, when computers were so expense that companies payed for batch processing instead of owning their own, FIFO was acceptable. (And for a tiny part of the market it still is.) But ever since the rise of time-sharing operating systems, users have come to expect short delays for small tasks. If you let one customer monopolize your capacity because they submitted a mountain of work before a second customer submits a handful, you probably won't have the second customer much longer.