<s>
XK7	B-Device
is	O
a	O
supercomputing	B-Architecture
platform	O
,	O
produced	O
by	O
Cray	O
,	O
launched	O
on	O
October	O
29	O
,	O
2012	O
.	O
</s>
<s>
XK7	B-Device
is	O
the	O
second	O
platform	O
from	O
Cray	O
to	O
use	O
a	O
combination	O
of	O
central	B-General_Concept
processing	I-General_Concept
units	I-General_Concept
(	O
"	O
CPUs	O
"	O
)	O
and	O
graphical	B-Architecture
processing	I-Architecture
units	I-Architecture
(	O
"	O
GPUs	B-Architecture
"	O
)	O
for	O
computing	O
;	O
the	O
hybrid	O
architecture	O
requires	O
a	O
different	O
approach	O
to	O
programming	O
to	O
that	O
of	O
CPU-only	O
supercomputers	B-Architecture
.	O
</s>
<s>
Laboratories	O
that	O
host	O
XK7	B-Device
machines	O
host	O
workshops	O
to	O
train	O
researchers	O
in	O
the	O
new	O
programming	O
languages	O
needed	O
for	O
XK7	B-Device
machines	O
.	O
</s>
<s>
The	O
platform	O
is	O
used	O
in	O
Titan	B-Device
,	O
the	O
world	O
's	O
second	O
fastest	B-Operating_System
supercomputer	I-Operating_System
in	O
the	O
November	O
2013	O
list	O
as	O
ranked	O
by	O
the	O
TOP500	B-Operating_System
organization	O
.	O
</s>
<s>
Other	O
customers	O
include	O
the	O
Swiss	O
National	O
Supercomputing	B-Architecture
Centre	O
which	O
has	O
a	O
272node	O
machine	O
and	O
Blue	B-Device
Waters	I-Device
has	O
a	O
machine	O
that	O
has	O
Cray	B-Device
XE6	I-Device
and	O
XK7	B-Device
nodes	O
that	O
performs	O
at	O
approximately	O
1petaFLOPS	O
(	O
1015	O
floating-point	O
operations	O
per	O
second	O
)	O
.	O
</s>
<s>
XK7	B-Device
is	O
scalable	O
up	O
to	O
500	O
cabinets	O
,	O
each	O
contains	O
24blades	O
and	O
each	O
blade	O
contains	O
4nodes	O
(	O
1CPU	O
and	O
1GPU	O
per	O
node	O
)	O
.	O
</s>
<s>
The	O
CPUs	O
available	O
are	O
of	O
the	O
16-core	O
AMD	O
Opteron	O
6200	O
Interlagos	O
series	O
and	O
the	O
GPUs	B-Architecture
are	O
of	O
the	O
Nvidia	B-Device
Tesla	I-Device
K20	O
Kepler	O
series	O
.	O
</s>
<s>
Each	O
CPU	O
can	O
be	O
paired	O
with	O
either	O
16	O
or	O
32GB	O
of	O
error-correcting	B-General_Concept
code	I-General_Concept
memory	I-General_Concept
(	O
ECC	B-General_Concept
)	O
while	O
the	O
GPUs	B-Architecture
have	O
either	O
5	O
or	O
6GB	O
of	O
ECC	B-General_Concept
memory	I-General_Concept
depending	O
on	O
the	O
model	O
of	O
GPU	B-Architecture
used	O
.	O
</s>
<s>
XK7	B-Device
based	O
machines	O
run	O
the	O
Cray	O
Linux	O
Environment	O
which	O
incorporates	O
SUSE	O
Linux	O
Enterprise	O
Server	O
.	O
</s>
<s>
Code	O
to	O
run	O
on	O
an	O
XK7	B-Device
machine	O
can	O
be	O
written	O
in	O
a	O
range	O
of	O
programming	O
languages	O
.	O
</s>
<s>
The	O
hybrid	O
architecture	O
requires	O
different	O
programming	O
to	O
conventional	O
CPU-only	O
supercomputers	B-Architecture
;	O
Oak	O
Ridge	O
National	O
Laboratory	O
and	O
the	O
Swiss	O
National	O
Supercomputing	B-Architecture
Centre	O
hold	O
workshops	O
to	O
educate	O
researchers	O
on	O
the	O
new	O
programming	O
approach	O
.	O
</s>
<s>
The	O
XK7	B-Device
platform	O
was	O
announced	O
on	O
October	O
29	O
,	O
2012	O
to	O
coincide	O
with	O
the	O
completion	O
of	O
Titan	B-Device
at	O
Oak	O
Ridge	O
National	O
Laboratory	O
(	O
ORNL	O
)	O
.	O
</s>
<s>
Titan	B-Device
has	O
18,688	O
XK7	B-Device
nodes	O
,	O
each	O
containing	O
an	O
Opteron6274	O
CPU	O
with	O
32GB	O
of	O
memory	O
and	O
a	O
K20X	O
GPU	B-Architecture
with	O
6GB	O
.	O
</s>
<s>
The	O
computer	O
has	O
a	O
theoretical	O
peak	O
performance	O
of	O
27.1petaFLOPS	O
but	O
in	O
the	O
LINPACK	B-Application
benchmark	O
used	O
by	O
the	O
TOP500	B-Operating_System
organisation	O
to	O
rank	O
supercomputers	B-Architecture
it	O
performed	O
at	O
17.59petaFLOPS	O
,	O
enough	O
to	O
take	O
first	O
place	O
on	O
the	O
November	O
2012	O
list	O
.	O
</s>
<s>
Titan	B-Device
uses	O
8.2MW	O
of	O
electricity	O
and	O
is	O
third	O
on	O
the	O
Green500	B-Application
list	O
which	O
ranks	O
supercomputers	B-Architecture
by	O
their	O
energy	O
efficiency	O
.	O
</s>
<s>
The	O
National	B-General_Concept
Center	I-General_Concept
for	I-General_Concept
Supercomputing	I-General_Concept
Applications	I-General_Concept
(	O
NCSA	O
)	O
in	O
Illinois	O
has	O
a	O
machine	O
,	O
Blue	B-Device
Waters	I-Device
,	O
using	O
a	O
combination	O
of	O
Cray	B-Device
XE6	I-Device
and	O
XK7	B-Device
nodes	O
.	O
</s>
<s>
The	O
XK7	B-Device
nodes	O
also	O
have	O
Opteron6276	O
CPUs	O
with	O
32GB	O
of	O
memory	O
and	O
a	O
K20X	O
GPU	B-Architecture
with	O
6GB	O
.	O
</s>
<s>
Blue	B-Device
Waters	I-Device
has	O
performed	O
at	O
over	O
1petaFLOPS	O
in	O
benchmarks	O
;	O
however	O
,	O
the	O
project	O
managers	O
do	O
not	O
believe	O
in	O
the	O
relevance	O
of	O
the	O
LINPACK	B-Application
benchmark	O
used	O
by	O
the	O
TOP500	B-Operating_System
organisation	O
and	O
therefore	O
did	O
not	O
submit	O
a	O
benchmark	O
test	O
for	O
ranking	O
.	O
</s>
<s>
The	O
Swiss	O
National	O
Supercomputing	B-Architecture
Centre	O
(	O
CSCS	O
)	O
machine	O
named	O
Todi	O
was	O
upgraded	O
to	O
XK7	B-Device
on	O
October	O
22	O
,	O
2012	O
.	O
</s>
<s>
Todi	O
has	O
272nodes	O
with	O
Opteron6272	O
CPUs	O
with	O
32GB	O
of	O
memory	O
and	O
a	O
K20X	O
GPU	B-Architecture
with	O
6GB	O
.	O
</s>
<s>
Todi	O
has	O
a	O
theoretical	O
peak	O
performance	O
of	O
393teraFLOPS	O
and	O
performed	O
at	O
274teraFLOPS	O
in	O
the	O
November	O
2012	O
TOP500	B-Operating_System
list	O
taking	O
91st	O
place	O
.	O
</s>
<s>
Todi	O
consumes	O
122kW	O
and	O
is	O
ranked	O
fourth	O
,	O
one	O
behind	O
Titan	B-Device
,	O
on	O
the	O
November	O
2012	O
Green500	B-Application
list	O
.	O
</s>
