L2 Miss Bound

Metric Description

The L2 is the last and longest-latency level in the memory hierarchy before the main memory (DRAM) or MCDRAM. Any memory requests missing here must be serviced by local or remote DRAM or MCDRAM, with significant latency. The L2 Miss Bound metric shows a ratio of cycles spent handling L2 misses to all cycles. The cycles spent handling L2 misses are calculated as L2 CACHE MISS COST * L2 CACHE MISS COUNT where L2 CACHE MISS COST is a constant measured as typical DRAM access latency in cycles.

Possible Issues

A high number of CPU cycles is being spent waiting for L2 load misses to be serviced.

Tips

1. Reduce the data working set size, improve data access locality, blocking and consuming data in chunks that fit into the L2, or better exploit hardware prefetchers.

2. Consider using software prefetchers but note that they can increase latency by interfering with normal loads, as well as increase pressure on the memory system.

For more complete information about compiler optimizations, see our Optimization Notice.
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