PERFMONCTL
Section: Linux Programmer's Manual (2)
Updated: 2017-09-15
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NAME
perfmonctl - interface to IA-64 performance monitoring unit
SYNOPSIS
#include <syscall.h>
#include <perfmon.h>
long perfmonctl(int fd, int cmd, void *arg, int narg);
Note:
There is no glibc wrapper for this system call; see NOTES.
DESCRIPTION
The IA-64-specific
perfmonctl()
system call provides an interface to the
PMU (performance monitoring unit).
The PMU consists of PMD (performance monitoring data) registers and
PMC (performance monitoring control) registers,
which gather hardware statistics.
perfmonctl()
applies the operation
cmd
to the input arguments specified by
arg.
The number of arguments is defined by narg.
The
fd
argument specifies the perfmon context to operate on.
Supported values for
cmd
are:
- PFM_CREATE_CONTEXT
-
perfmonctl(int fd, PFM_CREATE_CONTEXT, pfarg_context_t *ctxt, 1);
Set up a context.
-
The
fd
parameter is ignored.
A new perfmon context is created as specified in
ctxt
and its file descriptor is returned in ctxt->ctx_fd.
-
The file descriptor can be used in subsequent calls to
perfmonctl()
and can be used to read event notifications (type
pfm_msg_t)
using
read(2).
The file descriptor is pollable using
select(2),
poll(2),
and
epoll(7).
-
The context can be destroyed by calling
close(2)
on the file descriptor.
- PFM_WRITE_PMCS
-
perfmonctl(int fd, PFM_WRITE_PMCS, pfarg_reg_t *pmcs, n);
Set PMC registers.
- PFM_WRITE_PMDS
-
perfmonctl(int fd, PFM_WRITE_PMDS, pfarg_reg_t *pmds, n);
Set PMD registers.
- PFM_READ_PMDS
-
perfmonctl(int fd, PFM_READ_PMDS, pfarg_reg_t *pmds, n);
Read PMD registers.
- PFM_START
-
perfmonctl(int fd, PFM_START, NULL, 0);
Start monitoring.
- PFM_STOP
-
perfmonctl(int fd, PFM_STOP, NULL, 0);
Stop monitoring.
- PFM_LOAD_CONTEXT
-
perfmonctl(int fd, PFM_LOAD_CONTEXT, pfarg_load_t *largs, 1);
Attach the context to a thread.
- PFM_UNLOAD_CONTEXT
-
perfmonctl(int fd, PFM_UNLOAD_CONTEXT, NULL, 0);
Detach the context from a thread.
- PFM_RESTART
-
perfmonctl(int fd, PFM_RESTART, NULL, 0);
Restart monitoring after receiving an overflow notification.
- PFM_GET_FEATURES
-
perfmonctl(int fd, PFM_GET_FEATURES, pfarg_features_t *arg, 1);
- PFM_DEBUG
-
perfmonctl(int fd, PFM_DEBUG, val, 0);
If
val
is nonzero, enable debugging mode, otherwise disable.
- PFM_GET_PMC_RESET_VAL
-
perfmonctl(int fd, PFM_GET_PMC_RESET_VAL, pfarg_reg_t *req, n);
Reset PMC registers to default values.
RETURN VALUE
perfmonctl()
returns zero when the operation is successful.
On error, -1 is returned and
errno
is set to indicate the cause of the error.
VERSIONS
perfmonctl()
is available since Linux 2.4.
CONFORMING TO
perfmonctl()
is Linux-specific and is available only on the IA-64 architecture.
NOTES
Glibc does not provide a wrapper for this system call; call it using
syscall(2).
SEE ALSO
gprof(1)
The perfmon2 interface specification
COLOPHON
This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- VERSIONS
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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