When a Computer is run like a Bank

Firefox "crashed"!

Firefocks has Crashed

Sorry to hear that.

Why do you think it crashed?

Well, it was killed by the oom-killer according to my console.

Killed

It crashed!

This isn't technically a crash

What actually happened?

What does that mean?

Linux plays an amusing game... I can't remember if it's called Liar's Bluff or something else.

But to use a different expression: "the Kernel got caught with its pants down".

Who's the Colonel?

Oh, you've never served with him?

What would be a more current analogy?

Perhaps you're more familiar with Banks.

(This explanation was written on October 22, 2008.)

Banking

Think of your computer's OS like a bank.

Pick an Icelandic bank:

Icelandic banks collapse

The bank promises a series of loans/investments and banks on two things:

But in this case.... the bank made a promise and when investors (Firefox) came to collect the money (memory) to use it, the bank (OS) said: "Oops. I can't cover that loan."

What can the bank do?

It has a few choices:

Normally the bank just asks for a loan (swap) and is able to continue to function.

Sometimes loans can be too expensive, or maybe you configured the computer not to give them out....

What happens if it can't get a loan?

Then it has too do something about the current transaction.

Unlike a typical bank, the OS can fire/kill its customer.

psDoom

The real customer won't be very happy:

What can the bank do?

  1. The bank defaults on everyone (full panic, box is dead and may reboot or simply halt)
  2. You change the banking laws to refuse to allow overdrafts (/proc/sys/vm/overcommit_memory)
  3. You increase liquidity (enable swap, add swap)
  4. Offer "unlimited liquidity" in the form of dynamic swap (disk backed, not quite a federal reserve loan)