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System Calls - Manual Reference Pages  - PERFMONCTL (2)

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perfmonctl - interface to PMU

CONTENTS

Synopsis
Description
Availability

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#include <syscall.h> 
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#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:

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);
PFM_WRITE_PMDS
	set PMD registers perfmonctl(int fd, PFM_WRITE_PMDS , pfarg_pmd_t *pmds,n);
PFM_READ_PMDS
	read PMD registers perfmonctl(int fd, PFM_READ_PMDS , pfarg_pmd_t *pmds,n);
PFM_START
	start monitoring perfmonctl(int fd,PFM_START,arg,1); perfmonctl(int fd,PFM_START,NULL,0);
PFM_STOP
	stop monitoring perfmonctl(int fd,PFM_START,NULL,0);
PFM_LOAD_CONTEXT
	attach the context to a thread perfmonctl(int fd, PFM_LOAD_CONTEXT ,pfarg_load_t *largs,1);
PFM_UNLOAD_CONTEXT
	detach the context from a thread perfmonctl(int fd,PFM_UNLOAD_CONTEXT,NULL,0);
PFM_RESTART
	restart monitoring after recieving an overflow notification perfmonctl(int fd,PFM_RESTART,NULL,0);
PFM_CREATE_EVTSETS
	create or modify event sets perfmonctl(int fd,PFM_CREATE_EVTSETS,pfarg_setdesc_t*desc,n);
PFM_DELETE_EVTSETS
	delete event sets perfmonctl(int fd,PFM_DELETE_EVTSET,pfarg_setdesc_t*desc,n);
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 or go to Top of page |  Section 2 |  Main Man Index.