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GNU/Linux |
CentOS 5.4 |
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perfmonctl(2) |
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perfmonctl − interface to PMU
#include
<syscall.h>
#include <perfmon.h>
long perfmonctl(int fd, int cmd, void *arg, int narg);
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:
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PFM_CREATE_CONTEXT |
set up a context
perfmonctl(int fd, PFM_CREATE_CONTEXT ,
pfarg_context_t *ctxt, 1);
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.
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);
performctl returns zero when the operation is successful. On error -1 is returned and an error code is set in errno.
This syscall is implemented only on the IA-64 architecture since kernel 2.6.
gprof(1), The perfmon2 interface specification
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perfmonctl(2) | |