<s>
Portals	O
is	O
a	O
low-level	O
network	O
API	B-Application
for	O
high-performance	O
networking	O
on	O
high-performance	B-Architecture
computing	I-Architecture
systems	O
developed	O
by	O
Sandia	O
National	O
Laboratories	O
and	O
the	O
University	O
of	O
New	O
Mexico	O
.	O
</s>
<s>
Portals	O
is	O
currently	O
the	O
lowest-level	O
network	O
programming	B-Application
interface	I-Application
on	O
the	O
commercially	O
successful	O
XT	O
line	O
of	O
supercomputers	B-Architecture
from	O
Cray	O
.	O
</s>
<s>
Portals	O
provides	O
one-sided	O
data	O
movement	O
operations	O
,	O
but	O
unlike	O
other	O
one-sided	O
programming	B-Application
interfaces	I-Application
,	O
the	O
target	O
of	O
a	O
remote	O
operation	O
is	O
not	O
a	O
virtual	B-General_Concept
address	I-General_Concept
.	O
</s>
<s>
In	O
particular	O
,	O
Portals	O
is	O
aimed	O
at	O
providing	O
the	O
fundamental	O
operations	O
necessary	O
to	O
support	O
a	O
high-performance	O
and	O
scalable	O
implementation	O
of	O
the	O
Message	B-Application
Passing	I-Application
Interface	I-Application
(	O
MPI	O
)	O
standard	O
.	O
</s>
<s>
It	O
was	O
also	O
used	O
as	O
the	O
initial	O
network	O
transport	O
layer	O
for	O
the	O
Lustre	B-Application
file	O
system	O
.	O
</s>
<s>
Portals	O
began	O
in	O
the	O
early	O
1990s	O
as	O
an	O
extension	O
to	O
the	O
nX	B-Application
message	O
passing	O
system	O
used	O
in	O
the	O
SUNMOS	O
and	O
Puma	O
operating	O
system	O
.	O
</s>
<s>
It	O
was	O
first	O
implemented	O
for	O
the	O
Intel	B-Device
Paragon	I-Device
at	O
Sandia	O
,	O
and	O
later	O
ported	O
to	O
the	O
Intel	O
TeraFLOPS	O
machine	O
named	O
ASCI	B-Device
Red	I-Device
.	O
</s>
<s>
In	O
1999	O
,	O
an	O
operational	O
programming	B-Application
interface	I-Application
was	O
given	O
to	O
Portals	O
so	O
that	O
it	O
could	O
be	O
implemented	O
for	O
intelligent	O
or	O
programmable	O
network	O
interfaces	O
outside	O
of	O
a	O
lightweight	O
kernel	O
environment	O
.	O
</s>
<s>
The	O
Portals	O
3	O
specification	O
has	O
been	O
implemented	O
several	O
times	O
,	O
first	O
on	O
ASCI	B-Device
Red	I-Device
,	O
then	O
on	O
CPlant	O
over	O
Myrinet	B-General_Concept
,	O
Linux	B-Application
and	O
the	O
Cray	B-Device
XT	I-Device
family	O
.	O
</s>
<s>
In	O
light	O
of	O
emerging	O
partitioned	B-Application
global	I-Application
address	I-Application
space	I-Application
(	O
PGAS	O
)	O
languages	O
,	O
several	O
new	O
features	O
have	O
been	O
added	O
to	O
the	O
Portals	O
API	B-Application
as	O
part	O
of	O
Portals	O
4	O
.	O
</s>
<s>
Portals	O
4	O
is	O
the	O
low-level	O
networking	O
API	B-Application
for	O
the	O
Bull-Atos	O
BXI	O
NIC	O
.	O
</s>
