DCMD_PROF_ATTACH

Attach a process to the profiler

Synopsis:

#include <sys/dcmd_prof.h>

#define DCMD_PROF_ATTACH          __DIOT(_DCMD_MISC, PROF_ATTACH, struct __prof_clientinfo)

Arguments to devctl():

Argument	Value
`filedes`	A file descriptor for the profiler that you obtained by opening /dev/profiler.
`dcmd`	DCMD_PROF_ATTACH
`dev_data_ptr`	A pointer to a struct __prof_clientinfo (see below)
`n_bytes`	`sizeof(struct __prof_clientinfo)`
`dev_info_ptr`	NULL

Description:

This command attaches a process to the profiler.

The __prof_clientinfo structure is defined in <sys/profiler.h> as follows:

struct __prof_clientinfo {
    unsigned     cmd;          /* Command for this request */
    unsigned     cap_flags;    /* capabilities */
    unsigned     version;      /* Version of the profile code */
    int          reserved;
    uintptr_t    lowpc;        /* Low address for this mapping */
    uintptr_t    highpc;       /* High address for this mapping */
    void         *mcounts;     /* Address in process for count array if present */
    void         *arcdata;     /* Address in process for arc data if present */
    void         *bb_head;     /* Address in process for basic block info if present */
    int          from_off;     /* Offset in shared memory for the from structures */
    int          from_size;    /* Size of froms structures in bytes */
    int          tos_off;      /* Offset in shared memory for the tos structure */
    int          tos_size;     /* Size of tos structures in bytes */
    int          hash_frac;    /* Hash fraction for tos structures */
    int          shmem_key;    /* Key used to identify shared memory */
    int          map_name_len; /* name of mapping identifier if present */
    __FLEXARY(char, map_name); /* char map_name[] */
};

The bits for the cmd member include:

PROF_CMD_ADD_MAPPING — add a mapping to a running process.
PROF_CMD_ARCS — use the old style of arc, which linked a “from IP” to a “to”
PROF_CMD_ARCS_2 — use the current style of arc, which links a “to or self IP” to a “from” structure
PROF_CMD_INIT — not implemented
PROF_CMD_QUERY_THREAD — keep track of thread-level profiling information.
PROF_CMD_QUERY_SHLIB — try to profile shared libraries.
PROF_CMD_REMOVE_MAPPING — remove a mapping to a running process.

The bits for the cap_flags member include:

PROF_CAP_ARCCNTS — not used
PROF_CAP_BBINFO — read basic block information.
PROF_CAP_SAMPLER — not used
PROF_CAP_SHLIB — not used
PROF_CAP_THREAD — do thread-level function call accounting.

Normally, the executable puts the arc information in a shared memory object that has the form /dev/shmem/prof-pid-%d, where %d is the key. The profiler agent uses the information in shared memory to get call pairs, total call numbers, and so on.

The name of the mapping is passed in for information purposes. This is typically the basename of the executable for the main text segment, and the soname of libraries when passing in shared library information.

Input:

Output: