<s>
In	O
computing	O
,	O
unique	B-General_Concept
set	I-General_Concept
size	I-General_Concept
(	O
USS	O
)	O
is	O
the	O
portion	O
of	O
main	O
memory	O
(	O
RAM	B-Architecture
)	O
occupied	O
by	O
a	O
process	O
which	O
is	O
guaranteed	O
to	O
be	O
private	O
to	O
that	O
process	O
.	O
</s>
<s>
This	O
concept	O
is	O
used	O
for	O
software	O
running	O
under	O
the	O
Linux	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
The	O
concepts	O
of	O
resident	B-General_Concept
set	I-General_Concept
size	I-General_Concept
or	O
virtual	B-Architecture
memory	I-Architecture
size	O
(	O
VmSize	O
)	O
were	O
n't	O
helping	O
developers	O
who	O
tried	O
to	O
know	O
how	O
much	O
memory	O
their	O
programs	O
were	O
using	O
.	O
</s>
