<s>
In	O
computing	O
,	O
OProfile	B-Application
is	O
a	O
system-wide	O
statistical	O
profiling	O
tool	O
for	O
Linux	B-Operating_System
.	O
</s>
<s>
John	O
Levon	O
wrote	O
it	O
in	O
2001	O
for	O
Linux	B-Operating_System
kernel	I-Operating_System
version	O
2.4	O
after	O
his	O
M.Sc	O
.	O
</s>
<s>
project	O
;	O
it	O
consists	O
of	O
a	O
kernel	B-Operating_System
module	O
,	O
a	O
user-space	B-Operating_System
daemon	B-Operating_System
and	O
several	O
user-space	B-Operating_System
tools	O
.	O
</s>
<s>
OProfile	B-Application
can	O
profile	O
an	O
entire	O
system	O
or	O
its	O
parts	O
,	O
from	O
interrupt	B-General_Concept
routines	I-General_Concept
or	O
drivers	B-Application
,	O
to	O
user-space	B-Operating_System
processes	B-Operating_System
.	O
</s>
<s>
The	O
most	O
widely	O
supported	O
kernel	B-Operating_System
mode	O
of	O
uses	O
a	O
system	O
timer	O
(	O
See	O
:	O
Gathering	O
profiling	O
events	O
)	O
.	O
</s>
<s>
However	O
,	O
this	O
mode	O
is	O
unable	O
to	O
measure	O
kernel	B-Operating_System
functions	O
where	O
interrupts	B-Application
are	O
disabled	O
.	O
</s>
<s>
Newer	O
CPU	O
models	O
support	O
a	O
hardware	B-General_Concept
performance	I-General_Concept
counter	I-General_Concept
mode	O
which	O
uses	O
hardware	O
logic	O
to	O
record	O
events	O
without	O
any	O
active	O
code	O
needed	O
.	O
</s>
<s>
In	O
Linux	B-Operating_System
2.2/2.4	O
only	O
32-bit	O
x86	B-Operating_System
and	O
IA64	B-General_Concept
are	O
supported	O
;	O
in	O
Linux	B-Operating_System
2.6	I-Operating_System
there	O
is	O
wider	O
support	O
:	O
x86	B-Operating_System
(	O
32	O
and	O
64	O
bit	O
)	O
,	O
DEC	B-Device
Alpha	I-Device
,	O
MIPS	B-Device
,	O
ARM	B-Architecture
,	O
sparc64	B-Architecture
,	O
ppc64	B-General_Concept
,	O
AVR32	B-Device
.	O
</s>
<s>
Call	B-Application
graphs	I-Application
are	O
supported	O
only	O
on	O
x86	B-Operating_System
and	O
ARM	B-Architecture
.	O
</s>
<s>
In	O
2012	O
two	O
IBM	O
engineers	O
recognized	O
OProfile	B-Application
as	O
one	O
of	O
the	O
two	O
most	O
commonly	O
used	O
performance	B-General_Concept
counter	I-General_Concept
monitor	I-General_Concept
profiling	O
tools	O
on	O
Linux	B-Operating_System
,	O
alongside	O
perf	B-Application
tool	I-Application
.	O
</s>
<s>
In	O
2021	O
,	O
OProfile	B-Application
is	O
set	O
to	O
be	O
removed	O
from	O
version	O
5.12	O
of	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
with	O
the	O
user-space	B-Operating_System
tools	O
continuing	O
to	O
work	O
by	O
using	O
the	O
kernel	B-Operating_System
's	O
perf	B-Application
system	O
.	O
</s>
<s>
is	O
used	O
to	O
start	O
and	O
stop	O
the	O
daemon	B-Operating_System
,	O
which	O
collects	O
profiling	O
data	O
.	O
</s>
<s>
can	O
produce	O
annotated	O
sources	O
or	O
assembly	B-Language
.	O
</s>
<s>
converts	O
from	O
oprofile	B-Application
data	O
into	O
gprof-compatible	O
format	O
.	O
</s>
