dtrace_dtmalloc(4)

Usage

dtmalloc::function:malloc

dtmalloc::function:free

Overview

The dtmalloc provider instruments malloc(9) and free(9) kernel functions to trace memory allocations by type. Refer to malloc(9) for more details about malloc types.

The dtmalloc::function:malloc probe fires upon a successful allocation. Its probe arguments are:

Probe Argument	Definition
args[0]	struct malloc_type *mtp
args[1]	struct malloc_type_internal *mtip
args[2]	struct malloc_type_stats *mtsp
args[3]	unsigned long size
args[4]	int zindx

The dtmalloc::function:free probe fires upon a free operation. Its probe arguments are:

free Probe Argument	Definition
args[0]	struct malloc_type *mtp
args[1]	struct malloc_type_internal *mtip
args[2]	struct malloc_type_stats *mtsp
args[3]	unsigned long size
args[4]	Always 0

The first three arguments for each probe (i.e., mtp, mtip,, and mtsp) provide references to the malloc(9) type internals; size is the size of the allocation; zindx is the index into the kmemzones[] array used for the allocation. In practice, size is the most useful parameter to trace.

Implementation notes

The function part of the probe description in the dtmalloc provider is the malloc(9) type short description with all whitespace characters replaced with underscores. For example, a malloc type defined by

MALLOC_DEFINE(M_FOO_BAR, "foo bar", "FooBar subsystem");

will have probes called

dtmalloc::foo_bar:

Files

In sys/malloc.h: The header where struct malloc_type is defined.

Examples

Example 1 : Counting Successful Memory Allocations by Type

# dtrace -n 'dtmalloc:::malloc {@[stringof args[0]->ks_shortdesc] = count()}'
dtrace: description 'dtmalloc:::malloc ' matched 480 probes
^C
  80211node                                                         1
  CAM CCB                                                           1
  CAM periph                                                        1
  ioctlops                                                          1
  netlink                                                           1
  soname                                                            4
  sysctltmp                                                         4
  solaris                                                           5
  acpica                                                           16
  temp                                                             36
  lkpikmalloc                                                      44
  iov                                                             100
  selfd                                                           648

Caveats

The dtmalloc provider does not trace uma(9) allocations.

Referred to by