Universal Scaling Law

Original paper

When we can avoid or reduce the need for coordination things tend to get simpler and faster.

Where $C(N)$ is relative capacity

$C(N)=\frac{N}{1+\alpha (N-1)+\beta N(N-1)}$

• $N$ is the number of users/load generators
• Contention ($\propto \alpha$): effect of waiting or queueing for shared resources. When $\alpha =0$, we get linear scalability behaviour (e.g. lock-free computing)
• Coherency ($\propto \beta$): cost of getting agreement on what the right thing to do is (see also: authenticator complexity)

Share Nothing

Also called horizontal scaling or scaling out. Coordinate by communicating rather than sharing resources.

In effective leadership

Source

USL, couched in terms of ‘advice to leaders of fast-growing organisations.’

As a leader of a fast-growing company, in a fast-growing sector, you probably care about how much work your company can get done in a given unit of time (aka throughput), and also how long any one piece of work takes to get through the system (aka latency, or lead time).

• I always fall back to software engineering principles – particularly those around modularity – when it comes to thinking about organisation structure
  • You want strong cohesion within a group, and weak coupling between groups, you want to keep a handle on fan-out etc..
• The more operational decisions you need to be involved in, and the deeper you get involved, the more tasks you handle yourself, the higher your $\alpha$ coefficient and the more you limit the overall scalability of your organisation. So the first lesson is that it’s really important you learn to delegate effectively and to choose carefully the things that you do get involved in.