LLC Replacement Percentage
Metric Description
When a cache line is brought into the last-level
cache, another line must be evicted to make room for it. When lines in active
use are evicted, a performance problem may arise from continually rotating data
back into the cache. This metric measures the percentage of all replacements
due to each row. For example, if the grouping is set to 'Function', this metric
shows the percentage of all replacements due to each function, summing up to
100%.
Possible Issues
This row is responsible for a majority of all last-level cache
replacements. Some replacements are unavoidable, and a high level of
replacements may not indicate a problem. Consider this metric only when looking
for the source of a significant number of last-level cache misses for a
particular grouping. If these replacements are marked as a problem, try
rearranging data structures (for example, moving infrequently-used data away
from more-frequently-used data so that unused data is not taking up cache
space) or re-ordering operations (to get as much use as possible out of data
before it is evicted).