How to Deal with I/O Expense

There are two very fundamental techniques to improving I/O: caching and representation. Caching is avoiding I/O (generally avoiding the reading of some abstract value) by storing a copy of that value locally so no I/O is performed to get the value. The first key to caching is to make it crystal clear which data is the master and which are copies. There is only one master - period. Caching brings with it the danger that the copy sometimes can’t reflect changes to the master instantaneously.

Representations can often be improved by a factor of two or three from their first implementation. Techniques for doing this include using a binary representation instead of one that is human readable, transmitting a dictionary of symbols along with the data so that long symbols don’t have to be encoded, and, at the extreme, things like Huffman encoding.

Next How to Manage Memory