3.3. Branch Prediction Configurations

There are a number of parameters provided to govern the branch prediction in BOOM.

3.3.1. GShare Configuration Options Global History Length

How long of a history should be tracked? The length of the global history sets the size of the branch predictor. An -bit history pairs with a entry two-bit counter table.

3.3.2. TAGE Configurations Number of TAGE Tables

How many TAGE tables should be used? TAGE Table Sizes

What size should each TAGE table be? TAGE Table History Lengths

How long should the global history be for each table? This should be a geometrically increasing value for each table. TAGE Table Tag Sizes

What size should each tag be? TAGE Table U-bit Size

How many bits should be used to describe the usefulness of an entry?