<s>
Arm	B-Application
DDT	I-Application
is	O
a	O
commercial	O
C	B-Language
,	O
C++	B-Language
and	O
Fortran	B-Application
90	I-Application
debugger	B-Application
produced	O
by	O
Allinea	O
Software	O
now	O
part	O
of	O
Arm	B-Architecture
of	O
Warwick	B-Application
,	O
United	O
Kingdom	O
.	O
</s>
<s>
It	O
is	O
widely	O
used	O
for	O
debugging	O
parallel	B-Operating_System
Message	B-Application
Passing	I-Application
Interface	I-Application
(	O
MPI	O
)	O
and	O
threaded	O
(	O
pthread	B-Operating_System
or	O
OpenMP	B-Application
)	O
programs	O
,	O
including	O
those	O
running	O
on	O
clusters	B-Architecture
of	O
Linux	B-Application
machines	O
.	O
</s>
<s>
It	O
is	O
used	O
to	O
find	O
bugs	O
on	O
both	O
small	O
and	O
large	O
clusters	B-Architecture
,	O
from	O
1	O
to	O
100,000	O
s	O
of	O
processors	O
.	O
</s>
<s>
It	O
features	O
memory	B-General_Concept
debugging	I-General_Concept
which	O
detect	O
memory	B-Error_Name
leaks	I-Error_Name
,	O
or	O
reading	O
and	O
writing	O
beyond	O
the	O
bounds	O
of	O
arrays	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
debugger	B-Application
to	O
be	O
able	O
to	O
debug	O
petascale	B-General_Concept
applications	O
-	O
having	O
been	O
used	O
to	O
debug	O
applications	O
running	O
concurrently	O
on	O
220,000	O
processes	O
on	O
a	O
Cray	B-Device
XT5	I-Device
at	O
Oak	O
Ridge	O
National	O
Laboratories	O
.	O
</s>
<s>
This	O
is	O
possible	O
interactively	O
as	O
the	O
debugger	B-Application
's	O
control	O
tree	O
architecture	O
leads	O
to	O
logarithmic	O
performance	O
for	O
most	O
collective	O
operations	O
.	O
</s>
<s>
Arm	B-Application
DDT	I-Application
uses	O
the	O
GNU	B-Language
Debugger	I-Language
as	O
debug	O
engine	O
.	O
</s>
<s>
Arm	B-Application
DDT	I-Application
also	O
supports	O
coprocessor	O
architectures	O
such	O
as	O
Intel	B-General_Concept
Xeon	I-General_Concept
Phi	I-General_Concept
coprocessors	I-General_Concept
and	O
Nvidia	B-Architecture
CUDA	I-Architecture
GPUs	B-Architecture
.	O
</s>
<s>
It	O
is	O
part	O
of	O
Arm	B-Architecture
Forge	O
-	O
a	O
suite	O
of	O
tools	O
for	O
developing	O
code	O
in	O
high	O
performance	O
computing	O
-	O
which	O
also	O
includes	O
the	O
performance	O
profiler	O
for	O
scalar	O
,	O
multithreaded	O
and	O
parallel	B-Operating_System
codes	I-Operating_System
-	O
Arm	B-Architecture
MAP	O
.	O
</s>
<s>
,	O
80	O
percent	O
of	O
the	O
world	O
's	O
top	O
25	O
supercomputers	O
on	O
the	O
TOP500	B-Operating_System
list	O
,	O
use	O
Arm	B-Architecture
's	O
tools	O
.	O
</s>
