man pages section 3: Extended Library Functions, Volume 1

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Updated: July 2014
 
 

cpc_close (3CPC)

Name

cpc_open, cpc_close - initialize the CPU Performance Counter library

Synopsis

cc [ flag… ] file
–lcpc [ library… ] 
#include <libcpc.h>

cpc_t *cpc_open(int 
vers);
int cpc_close(cpc_t *
cpc);

Description

The cpc_open() function initializes libcpc(3LIB) and returns an identifier that must be used as the cpc argument in subsequent libcpc function calls. The cpc_open () function takes an interface version as an argument and returns NULL if that version of the interface is incompatible with the libcpc implementation present on the system. Usually, the argument has the value of CPC_VER_CURRENT bound to the application when it was compiled.

If cpc_open() function is called with CPC_VER_CURRENT, and if the system supports both the CPU performance counter (cpc) and the hardware sampling (SMPL), cpc_open() function initializes both CPC and SMPL. The returned identifier can be used as the cpc argument in subsequent libcpc function calls that require the SMPL functionality. If the system supports only CPC, cpc_open() function initializes only CPC. The returned identifier can be used as the cpc argument in subsequent libcpc function calls that do not require the SMPL functionality.

If cpc_open() function is called with CPC_VER_CPC_ONLY , cpc_open()function initializes only CPC, whether the system supports SMPL in addition to CPC or not.

The following macros can be specified to cpc_open() as vers:

CPC_VER_CURRENT

If the system supports SMPL in addition to CPC, cpc_open() initializes both CPC and SMPL. Otherwise, cpc_open () initializes only CPC.

CPC_VER_CPC_ONLY

cpc_open() initializes only CPC whether the system support SMPL in addition to CPC or not.

The cpc_close() function releases all resources associated with the cpc argument. Any bound counters and hardware sampling utilized by the process are unbound. All entities of type cpc_set_t and cpc_buf_t are invalidated and destroyed.

Return Values

If the version requested is supported by the implementation, cpc_open() returns a cpc_t handle for use in all subsequent libcpc operations. If the implementation cannot support the version needed by the application, cpc_open() returns NULL, indicating that the application at least needs to be recompiled to operate correctly on the new platform and might require further changes.

The cpc_close() function always returns 0.

Errors

These functions will fail if:

EINVAL

The version requested by the client is incompatible with the implementation.

Attributes

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

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
MT-Level
Safe

See Also

libcpc(3LIB) , attributes (5)