<s>
is	O
a	O
Linux-specific	O
system	B-Operating_System
call	I-Operating_System
that	O
moves	O
data	O
between	O
a	O
file	B-Application
descriptor	I-Application
and	O
a	O
pipe	O
without	O
a	O
round	O
trip	O
to	O
user	O
space	O
.	O
</s>
<s>
The	O
related	O
system	B-Operating_System
call	I-Operating_System
moves	O
or	O
copies	O
data	O
between	O
a	O
pipe	O
and	O
user	O
space	O
.	O
</s>
<s>
Ideally	O
,	O
splice	B-Application
and	O
vmsplice	O
work	O
by	O
remapping	O
pages	O
and	O
do	O
not	O
actually	O
copy	O
any	O
data	O
,	O
which	O
may	O
improve	O
I/O	B-General_Concept
performance	O
.	O
</s>
<s>
With	O
,	O
one	O
can	O
move	O
data	O
from	O
one	O
file	B-Application
descriptor	I-Application
to	O
another	O
without	O
incurring	O
any	O
copies	O
from	O
user	O
space	O
into	O
kernel	O
space	O
,	O
which	O
is	O
usually	O
required	O
to	O
enforce	O
system	O
security	O
and	O
also	O
to	O
keep	O
a	O
simple	O
interface	O
for	O
processes	O
to	O
read	O
and	O
write	O
to	O
files	O
.	O
</s>
<s>
works	O
by	O
using	O
the	O
pipe	B-Operating_System
buffer	I-Operating_System
.	O
</s>
<s>
A	O
pipe	B-Operating_System
buffer	I-Operating_System
is	O
an	O
in-kernel	O
memory	O
buffer	O
that	O
is	O
opaque	O
to	O
the	O
user	O
space	O
process	O
.	O
</s>
<s>
A	O
user	O
process	O
can	O
splice	B-Application
the	O
contents	O
of	O
a	O
source	O
file	O
into	O
this	O
pipe	B-Operating_System
buffer	I-Operating_System
,	O
then	O
splice	B-Application
the	O
pipe	B-Operating_System
buffer	I-Operating_System
into	O
the	O
destination	O
file	O
,	O
all	O
without	O
moving	O
any	O
data	O
through	O
userspace	O
.	O
</s>
<s>
Linus	O
Torvalds	O
described	O
in	O
a	O
2006	O
email	O
,	O
which	O
was	O
included	O
in	O
a	O
KernelTrap	B-Application
article	O
.	O
</s>
<s>
The	O
Linux	B-Application
splice	B-Application
implementation	O
borrows	O
some	O
ideas	O
from	O
an	O
original	O
proposal	O
by	O
Larry	O
McVoy	O
in	O
1998	O
.	O
</s>
<s>
The	O
splice	B-Application
system	B-Operating_System
calls	I-Operating_System
first	O
appeared	O
in	O
Linux	B-Application
kernel	O
version	O
2.6.17	O
and	O
were	O
written	O
by	O
Jens	O
Axboe	O
.	O
</s>
<s>
This	O
is	O
an	O
example	O
of	O
splice	B-Application
in	O
action	O
:	O
</s>
<s>
is	O
one	O
of	O
three	O
system	B-Operating_System
calls	I-Operating_System
that	O
complete	O
the	O
architecture	O
.	O
</s>
<s>
can	O
map	O
an	O
application	O
data	O
area	O
into	O
a	O
pipe	O
(	O
or	O
vice	O
versa	O
)	O
,	O
thus	O
allowing	O
transfers	O
between	O
pipes	B-Operating_System
and	O
user	O
memory	O
where	O
transfers	O
between	O
a	O
file	B-Application
descriptor	I-Application
and	O
a	O
pipe	O
.	O
</s>
<s>
It	O
duplicates	O
one	O
pipe	O
to	O
another	O
,	O
enabling	O
forks	O
in	O
the	O
way	O
applications	O
are	O
connected	O
with	O
pipes	B-Operating_System
.	O
</s>
<s>
When	O
using	O
with	O
sockets	O
,	O
the	O
network	O
controller	O
(	O
NIC	O
)	O
should	O
support	O
DMA	O
,	O
otherwise	O
splice( )	O
will	O
not	O
deliver	O
a	O
large	O
performance	O
improvement	O
.	O
</s>
