<s>
Communication-avoiding	B-Operating_System
algorithms	I-Operating_System
minimize	O
movement	O
of	O
data	O
within	O
a	O
memory	B-General_Concept
hierarchy	I-General_Concept
for	O
improving	O
its	O
running-time	O
and	O
energy	O
consumption	O
.	O
</s>
<s>
A	O
common	O
computational	O
model	O
in	O
analyzing	O
communication-avoiding	B-Operating_System
algorithms	I-Operating_System
is	O
the	O
two-level	O
memory	O
model	O
:	O
</s>
<s>
Technological	O
trends	O
indicate	O
that	O
the	O
relative	O
cost	O
of	O
communication	O
is	O
increasing	O
on	O
a	O
variety	O
of	O
platforms	O
,	O
from	O
cloud	B-Architecture
computing	I-Architecture
to	O
supercomputers	B-Architecture
to	O
mobile	O
devices	O
.	O
</s>
<s>
Energy	O
consumption	O
increases	O
by	O
orders	O
of	O
magnitude	O
as	O
we	O
go	O
higher	O
in	O
the	O
memory	B-General_Concept
hierarchy	I-General_Concept
.	O
</s>
<s>
United	O
States	O
president	O
Barack	O
Obama	O
cited	O
communication-avoiding	B-Operating_System
algorithms	I-Operating_System
in	O
the	O
FY	O
2012	O
Department	O
of	O
Energy	O
budget	O
request	O
to	O
Congress	O
:	O
</s>
<s>
Communication-avoiding	B-Operating_System
algorithms	I-Operating_System
are	O
designed	O
with	O
the	O
following	O
objectives	O
:	O
</s>
<s>
Reorganize	O
algorithms	O
to	O
reduce	O
communication	O
across	O
all	O
memory	B-General_Concept
hierarchies	I-General_Concept
.	O
</s>
<s>
Fast	O
memory	O
may	O
be	O
defined	O
as	O
the	O
local	O
processor	O
memory	O
(	O
CPU	B-General_Concept
cache	I-General_Concept
)	O
of	O
size	O
M	O
and	O
slow	O
memory	O
may	O
be	O
defined	O
as	O
the	O
DRAM	O
.	O
</s>
<s>
Cache-oblivious	B-Application
algorithms	I-Application
represent	O
a	O
different	O
approach	O
introduced	O
in	O
1999	O
for	O
fast	O
Fourier	O
transforms	O
,	O
and	O
then	O
extended	O
to	O
graph	O
algorithms	O
,	O
dynamic	O
programming	O
,	O
etc	O
.	O
</s>
