cpc_enable(3CPC) cpc_enable(3CPC)
NAME
cpc_enable, cpc_disable - enable and disable performance counters
SYNOPSIS
cc [ flag... ] file... -lcpc [ library... ]
#include <libcpc.h>
int cpc_enable(cpc_t *cpc);
int cpc_disable(cpc_t *cpc);
In certain applications, it can be useful to explicitly enable and disable performance counters at different times so that the performance
of a critical algorithm can be examined. The cpc_enable() and cpc_disable() functions can be used to enable and disable the performance
counters without otherwise disturbing the invoking LWP's performance hardware configuration.
Upon successful completion, cpc_enable() and cpc_disable() return 0. Otherwise, they return -1 and set errno to indicate the error.
These functions will fail if:
EAGAIN The associated performance counter context has been invalidated by another process.
EINVAL No performance counter context has been created for the calling LWP.
Example 1: Use cpc_enable and cpc_disable to minimize code needed by application.
In the following example, the cpc_enable() and cpc_disable() functions are used to minimize the amount of code that needs to be added to
the application. The cputrack(1) command can be used in conjunction with these functions to provide event programming, sampling, and
reporting facilities.
If the application is instrumented in this way and then started by cputrack with the nouser flag set in the event specification, counting
of user events will only be enabled around the critical code section of interest. If the program is run normally, no harm will ensue.
int
main(int argc, char *argv[])
{
cpc_t *cpc = cpc_open(CPC_VER_CURRENT);
/* ... application code ... */
if (cpc != NULL)
(void) cpc_enable(cpc);
/* ==> Code to be measured goes here <== */
if (cpc != NULL)
(void) cpc_disable(cpc);
/* ... other application code */
}
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Evolving |
+-----------------------------+-----------------------------+
|MT-Level |Safe |
+-----------------------------+-----------------------------+
cputrack(1), cpc(3CPC), cpc_open(3CPC), libcpc(3LIB), attributes(5)
31 Jan 2005 cpc_enable(3CPC)