Independent tuning of multiple hardware prefetchers

A method comprising:

• requesting, by a first hardware prefetcher, a first prefetch of a line of data;
• setting a first indicator in a fill buffer entry to indicate that the line of data is requested by the first hardware prefetcher;
• incrementing a first prefetch counter in response to setting the first indicator, the first prefetch counter corresponding to the first hardware prefetcher;
• requesting, by a second hardware prefetcher, a second prefetch of the line of data;
• setting a second indicator in the fill buffer entry to indicate that the line of data is also requested by the second hardware prefetcher;
• and
• incrementing a second prefetch counter in response to setting the second indicator, the second prefetch counter corresponding to the second hardware prefetcher.

A system comprising:

• a system memory;
• a processor including:
• a processor core;
• a cache memory;
• a first hardware prefetcher to prefetch data for the processor core from the system memory to the cache memory;
• a prefetch tuner to adjust a first prefetch rate of the first hardware prefetcher based on a first fraction of late prefetches, the prefetch tuner including a first late prefetch counter to count a first number of late prefetches for the first hardware prefetcher, a first prefetch counter to count a first number of prefetches for the first hardware prefetcher, and a late prefetch calculator to calculate the first fraction of late prefetches based on the first number of late prefetches and the first number of prefetches.