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perfmonctl() - Unix, Linux System Call
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NAME
perfmonctl - interface to PMU
SYNOPSIS
#include <syscall.h>
#include <perfmon.h>
long perfmonctl(int fd, int cmd, void *arg, int narg);
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DESCRIPTION
perfmonctl system call provides an interface to PMU (performance monitoring unit).
PMU consists of PMD (performance monitoring data) registers and
PMC (performance monitoring control) registers, where are
gathered the hardware statistic.
perfmonctl will apply a function
cmd to input arguments
arg. The number of arguments is defined by input variable narg.
fd specifies the perfmon context to operate on.
The implemented commands
cmd are:
| Tag | Description |
|---|
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PFM_CREATE_CONTEXT | | |
set up a context
perfmonctl(int fd, PFM_CREATE_CONTEXT , pfarg_context_t *ctxt,1);
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The
fd parameter is ignored. A new context is created as specified in
ctxt and its file descriptor is returned in ctxt->ctx_fd.
The file descriptor, apart from passing it to perfmonctl,
can be used to read event notifications (type
pfm_msg_t) using the
read(2)
system call.
Both
select(2)
and
poll(2)
can be used to wait for event notifications.
The context can be destroyed using the
close(2)
system call.
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PFM_WRITE_PMCS | | |
set PMC registers
perfmonctl(int fd, PFM_WRITE_PMCS , pfarg_pmc_t *pmcs,n);
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PFM_WRITE_PMDS | | |
set PMD registers
perfmonctl(int fd, PFM_WRITE_PMDS , pfarg_pmd_t *pmds,n);
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PFM_READ_PMDS | | |
read PMD registers
perfmonctl(int fd, PFM_READ_PMDS , pfarg_pmd_t *pmds,n);
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PFM_START | | |
start monitoring
perfmonctl(int fd,PFM_START,arg,1);
perfmonctl(int fd,PFM_START,NULL,0);
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PFM_STOP | | |
stop monitoring
perfmonctl(int fd,PFM_START,NULL,0);
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PFM_LOAD_CONTEXT | | |
attach the context to a thread
perfmonctl(int fd, PFM_LOAD_CONTEXT ,pfarg_load_t *largs,1);
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PFM_UNLOAD_CONTEXT | | |
detach the context from a thread
perfmonctl(int fd,PFM_UNLOAD_CONTEXT,NULL,0);
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PFM_RESTART | | |
restart monitoring after recieving an overflow notification
perfmonctl(int fd,PFM_RESTART,NULL,0);
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PFM_CREATE_EVTSETS | | |
create or modify event sets
perfmonctl(int fd,PFM_CREATE_EVTSETS,pfarg_setdesc_t*desc,n);
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PFM_DELETE_EVTSETS | | |
delete event sets
perfmonctl(int fd,PFM_DELETE_EVTSET,pfarg_setdesc_t*desc,n);
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PFM_GETINFO_EVTSETS | | |
get information about event sets
perfmonctl(int fd,PFM_GETINFO_EVTSETS,pfarg_setinfo_t*info,n);
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RETURN VALUE
performctl returns zero when the operation is successful.
On error -1 is returned and an error code is set in errno.
AVAILABILITY
This syscall is implemented only on the IA-64 architecture since kernel 2.6.
SEE ALSO
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