<s>
In	O
computing	O
,	O
vectored	B-General_Concept
I/O	I-General_Concept
,	O
also	O
known	O
as	O
scatter/gather	B-General_Concept
I/O	I-General_Concept
,	O
is	O
a	O
method	O
of	O
input	B-General_Concept
and	I-General_Concept
output	I-General_Concept
by	O
which	O
a	O
single	O
procedure	O
call	O
sequentially	O
reads	O
data	O
from	O
multiple	O
buffers	B-General_Concept
and	O
writes	O
it	O
to	O
a	O
single	O
data	B-General_Concept
stream	I-General_Concept
,	O
or	O
reads	O
data	O
from	O
a	O
data	B-General_Concept
stream	I-General_Concept
and	O
writes	O
it	O
to	O
multiple	O
buffers	B-General_Concept
,	O
as	O
defined	O
in	O
a	O
vector	B-Data_Structure
of	O
buffers	B-General_Concept
.	O
</s>
<s>
Scatter/gather	B-General_Concept
refers	O
to	O
the	O
process	B-Operating_System
of	O
gathering	O
data	O
from	O
,	O
or	O
scattering	O
data	O
into	O
,	O
the	O
given	O
set	O
of	O
buffers	B-General_Concept
.	O
</s>
<s>
Vectored	B-General_Concept
I/O	I-General_Concept
can	O
operate	O
synchronously	O
or	O
asynchronously	O
.	O
</s>
<s>
The	O
main	O
reasons	O
for	O
using	O
vectored	B-General_Concept
I/O	I-General_Concept
are	O
efficiency	O
and	O
convenience	O
.	O
</s>
<s>
Vectored	B-General_Concept
I/O	I-General_Concept
has	O
several	O
potential	O
uses	O
:	O
</s>
<s>
Concatenating	O
output	O
:	O
an	O
application	O
that	O
wants	O
to	O
write	O
non-sequentially	O
placed	O
data	O
in	O
memory	O
can	O
do	O
so	O
in	O
one	O
vectored	B-General_Concept
I/O	I-General_Concept
operation	O
.	O
</s>
<s>
The	O
Windows	B-Library
API	I-Library
has	O
analogous	O
functions	O
ReadFileScatter	O
and	O
WriteFileGather	O
;	O
however	O
,	O
unlike	O
the	O
POSIX	O
functions	O
,	O
they	O
require	O
the	O
alignment	O
of	O
each	O
buffer	B-General_Concept
on	O
a	O
memory	B-General_Concept
page	I-General_Concept
.	O
</s>
<s>
Winsock	B-Application
provides	O
separate	O
WSASend	O
and	O
WSARecv	O
functions	O
without	O
this	O
requirement	O
.	O
</s>
<s>
Each	O
word	O
is	O
saved	O
into	O
a	O
single	O
buffer	B-General_Concept
and	O
with	O
only	O
one	O
call	O
to	O
writev( )	O
,	O
all	O
buffers	B-General_Concept
are	O
printed	O
to	O
the	O
standard	O
output	O
.	O
</s>
