6.3.3 Snoop filter events

There are three snoop events that can be counted.

The following sections describe the snoop filter performance events.

Snoop filter miss rate

This event measures the amount of memory controller traffic that is generated. It can also be used to measure the efficiency of the snoop filter.

PMU_HN_SF_HIT_EVENTMeasures the number of snoop filter hits.

Calculate the snoop filter hit rate as follows:

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Snoop filter accesses are only counted for first-time lookups, and not for the victim selection accesses or snoop filter fills. Because the L3 lookup and snoop filter lookups are parallel, the L3 lookups can be used to calculate the snoop filter hit rate.

Snoop filter evictions

This event measures the frequency of snoop filter evictions, and determines the DEQ size.

PMU_HN_SF_EVICTIONS_EVENTMeasures the number of snoop filter evictions when cache invalidations are initiated.

Snoops sent and received with hit rate

This event measures the amount of shared data across clusters for a specific application, using snoops hits or misses.

PMU_HN_SNOOPS_SENT_EVENTNumber of snoops sent. Does not differentiate between broadcast or directed snoops.
PMU_HN_SNOOPS_BROADCAST_EVENTNumber of snoop broadcasts sent.

Calculate the snoops sent and received rate as follows:

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The number of broadcast and total snoops measures the shared data invalidations.

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