Format of the Well-Known Hardware Counter List

In the well-known hardware counter list, the first field (for example, cycles) gives the alias name that can be used in the -h counter... argument of the collect command. This alias name is also the identifier to use in the er_print command.

The second field lists the available registers for the counter; for example, [/{0|1}]. For well-known counters, the default value has been chosen to provide a reasonable sample rate. Because actual rates vary considerably, you might need to specify a non-default value.

The third field, for example, 9999991, is the default overflow value for the counter.

The fourth field, in parentheses, contains type information. It provides a short description (for example, CPU Cycles), the raw hardware counter name (for example, Cycle_cnt), and the type of units being counted (for example, CPU-cycles), which can include up to two words.

If the first word of type information is:

• load, store, or load-store, the counter is memory-related. You can prepend a + sign to the counter name (for example, +dcrm) in the collect -h command, to request a search for the precise instruction and virtual address that caused the event. The + sign also enables dataspace profiling; see The DataObjects Tab, The DataLayout Tab, and The MemoryObjects Tabs for details.

• not-program-related, the counter captures events initiated by some other program, such as CPU-to-CPU cache snoops. Using the counter for profiling generates a warning and profiling does not record a call stack.

If the second or only word of the type information is:

• CPU-cycles, the counter can be used to provide a time-based metric. The metrics reported for such counters are converted by default to inclusive and exclusive times, but can optionally be shown as event counts.

• events, the metric is inclusive and exclusive event counts, and cannot be converted to a time.

In the well-known hardware counter list in the example, the type information contains one word, CPU-cycles for the first counter and events for the second counter. For the third counter, the type information contains two words, load events.