CPC_ENABLE(3CPC) CPU Performance Counters Library Functions 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);
DESCRIPTION
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.
RETURN VALUES
Upon successful completion,
cpc_enable() and
cpc_disable() return 0.
Otherwise, they return -1 and set
errno to indicate the error.
ERRORS
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.
EXAMPLES
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 */
}
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Evolving |
+--------------------+-----------------+
|MT-Level | Safe |
+--------------------+-----------------+
SEE ALSO
cputrack(1),
cpc(3CPC),
cpc_open(3CPC),
libcpc(3LIB),
attributes(7) January 31, 2005
CPC_ENABLE(3CPC)