man pages section 3: Extended Library Functions, Volume 1

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Updated: July 2014



cpc_event - data structure to describe CPU performance counters


#include <libcpc.h>


The libcpc interfaces manipulate CPU performance counters using the cpc_event_t data structure. This structure contains several fields that are common to all processors, and some that are processor-dependent. These structures can be declared by a consumer of the API, thus the size and offsets of the fields and the entire data structure are fixed per processor for any particular version of the library. See cpc_version(3CPC) for details of library versioning.


For UltraSPARC, the structure contains the following members:

typedef struct {
        int ce_cpuver;
        hrtime_t ce_hrt;
        uint64_t ce_tick;
        uint64_t ce_pic[2];
        uint64_t ce_pcr;
} cpc_event_t;


For Pentium, the structure contains the following members:

typedef struct {
        int ce_cpuver;
        hrtime_t ce_hrt;
        uint64_t ce_tsc;
        uint64_t ce_pic[2];
        uint32_t ce_pes[2];
#define ce_cesr ce_pes[0]
} cpc_event_t;

The APIs are used to manipulate the highly processor-dependent control registers (the ce_pcr, ce_cesr, and ce_pes fields); the programmer is strongly advised not to reference those fields directly in portable code. The ce_pic array elements contain 64-bit accumulated counter values. The hardware registers are virtualized to 64-bit quantities even though the underlying hardware only supports 32-bits (UltraSPARC) or 40-bits (Pentium) before overflow.

The ce_hrt field is a high resolution timestamp taken at the time the counters were sampled by the kernel. This uses the same timebase as gethrtime(3C) .

On SPARC V9 machines, the number of cycles spent running on the processor is computed from samples of the processor-dependent %tick register, and placed in the ce_tick field. On Pentium processors, the processor-dependent time-stamp counter register is similarly sampled and placed in the ce_tsc field.


See attributes(5) for descriptions of the following attributes:

Interface Stability

See also

gethrtime(3C), cpc(3CPC), cpc_version(3CPC), libcpc(3LIB), attributes(5)