NAME
pmc_attach, pmc_detach – attaching and detaching process scope PMCs to target processes
LIBRARY
library “libpmc”
SYNOPSIS
#include <pmc.h>
int
pmc_attach(pmc_id_t pmcid, pid_t pid);
int
pmc_detach(pmc_id_t pmcid, pid_t pid);
DESCRIPTION
These functions control the set of target processes tracked by a process scope PMC.
Function pmc_attach() is used to attach a process scope PMC specified by argument pmcid to a target process specified by argument pid. Argument pid may be zero to denote the current process. If the PMC was allocated with modifier PMC_F_DESCENDANTS, the PMC will additionally attach to current and future descendents of the specified target process. The PMC should be in a quiescent state (i.e., not running).
Function pmc_detach() is used to detach a process scope PMC specified by argument pmcid from a process specified by argument pid. Argument pid may be zero to denote the current process.
RETURN VALUES
The pmc_attach() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
ERRORS
A call to function pmc_attach() may fail with the following errors:
- [EBUSY]
-
Argument pmcid specified a PMC that was not in a quiescent state.
- [EBUSY]
-
The target process specified by function pmc_attach is being tracked by another process scope PMC that uses the same PMC hardware resources.
- [EEXIST]
-
The target process is already being tracked by the specified PMC.
- [EINVAL]
-
Argument pmcid specified a PMC with system scope.
- [EINVAL]
-
Argument pid specified an illegal process id.
- [EINVAL]
-
The current process does not own a PMC with the handle specified in argument pmcid.
- [EPERM]
-
The caller lacked the privilege needed to attach PMCs to the specified target process.
- [EPERM]
-
(i386 and amd64 architectures) The PMC specified by argument pmcid has been setup to allow the use of the RDPMC instruction for self measurement.
- [ESRCH]
-
The current process does not own any PMCs.
- [ESRCH]
-
The process specified by argument pid did not exist.
A call to function pmc_detach() may fail with the following errors:
- [EINVAL]
-
Argument pmcid specified a PMC with system scope.
- [EINVAL]
-
Argument pid specified an illegal process id.
- [EINVAL]
-
The current process does not own a PMC with the handle specified in argument pmcid.
- [EINVAL]
-
The specified PMC was not attached to the target process.
- [ESRCH]
-
The current process does not own any PMCs.
- [ESRCH]
-
The process specified by argument pid is not being monitored by hwpmc(4).
- [ESRCH]
-
The process specified by argument pid did not exist.