Speed

That infinite space “between” what we humans feel as time is where computers spend all their time. It’s an entirely different timescale. A great table that illustrates just how enormous these time differentials are. Just translate computer time into arbitrary seconds:

A great table that illustrates just how enormous these time differentials are. Just translate computer time into arbitrary seconds:

1 CPU cycle0.3 ns1 s
Level 1 cache access0.9 ns3 s
Level 2 cache access2.8 ns9 s
Level 3 cache access12.9 ns43 s
Main memory access120 ns6 min
Solid-state disk I/O50-150 μs2-6 days
Rotational disk I/O1-10 ms1-12 months
Internet: SF to NYC40 ms4 years
Internet: SF to UK81 ms8 years
Internet: SF to Australia183 ms19 years
OS virtualization reboot4 s423 years
SCSI command time-out30 s3000 years
Hardware virtualization reboot40 s4000 years
Physical system reboot5 m32 millenia

Approximate timing for various operations on a typical PC:

execute typical instruction 1/1,000,000,000 sec = 1 nanosec
fetch from L1 cache memory 0.5 nanosec
branch misprediction 5 nanosec
fetch from L2 cache memory 7 nanosec
Mutex lock/unlock 25 nanosec
fetch from main memory 100 nanosec
send 2K bytes over 1Gbps network 20,000 nanosec
read 1MB sequentially from memory 250,000 nanosec
fetch from new disk location (seek) 8,000,000 nanosec
read 1MB sequentially from disk 20,000,000 nanosec
send packet US to Europe and back 150 milliseconds = 150,000,000 nanosec

Latency is one thing, but it’s also worth considering the cost of that bandwidth.

An interesting way of explaining this. If the CPU registers are how long it takes you to fetch data from your brain, then going to disk is the equivalent of fetching data from Pluto.

https://blog.codinghorror.com/content/images/2014/May/storage-latency-how-far-away-is-the-data.png
  • Distance to Pluto: 4.67 billion miles.
  • Latest fastest spinning HDD performance (49.7) versus latest fastest PCI Express SSD (506.8). That’s an improvement of 10x.
  • New distance: 467 million miles.
  • Distance to Jupiter: 500 million miles.

That’s disk performance over the last decade. How much faster did CPUs, memory, and networks get in the same time frame? Would a 10x or 100x improvement really make a dent in these vast infinite spaces in time that computers deal with?

To computers, we humans work on a completely different time scale, practically geologic time. Which is completely mind-bending. The faster computers get, the bigger this time disparity grows.