<s>
Generalized	B-Algorithm
processor	I-Algorithm
sharing	I-Algorithm
(	O
GPS	O
)	O
is	O
an	O
ideal	O
scheduling	O
algorithm	O
for	O
process	O
schedulers	O
and	O
network	B-Application
schedulers	I-Application
.	O
</s>
<s>
In	O
process	O
scheduling	O
,	O
GPS	O
is	O
"	O
an	O
idealized	O
scheduling	O
algorithm	O
that	O
achieves	O
perfect	O
fairness	B-Protocol
.	O
</s>
<s>
All	O
practical	O
schedulers	O
approximate	O
GPS	O
and	O
use	O
it	O
as	O
a	O
reference	O
to	O
measure	O
fairness.	O
"	O
</s>
<s>
Generalized	B-Algorithm
processor	I-Algorithm
sharing	I-Algorithm
assumes	O
that	O
traffic	O
is	O
fluid	O
(	O
infinitesimal	O
packet	O
sizes	O
)	O
,	O
and	O
can	O
be	O
arbitrarily	O
split	O
.	O
</s>
<s>
There	O
are	O
several	O
service	O
disciplines	O
which	O
track	O
the	O
performance	O
of	O
GPS	O
quite	O
closely	O
such	O
as	O
weighted	B-Algorithm
fair	I-Algorithm
queuing	I-Algorithm
(	O
WFQ	B-Algorithm
)	O
,	O
also	O
known	O
as	O
packet-by-packet	O
generalized	B-Algorithm
processor	I-Algorithm
sharing	I-Algorithm
(	O
PGPS	O
)	O
.	O
</s>
<s>
For	O
example	O
,	O
email	O
is	O
a	O
genuinely	O
store	B-Protocol
and	I-Protocol
forward	I-Protocol
kind	O
of	O
application	O
,	O
but	O
videoconferencing	B-Application
is	O
n't	O
since	O
it	O
requires	O
low	O
latency	O
.	O
</s>
<s>
Generalized	B-Algorithm
processor	I-Algorithm
sharing	I-Algorithm
assumes	O
that	O
the	O
traffic	O
is	O
fluid	O
,	O
i.e.	O
,	O
infinitely	O
divisible	O
so	O
that	O
whenever	O
an	O
application	O
type	O
has	O
packets	O
in	O
the	O
queue	O
,	O
it	O
will	O
receive	O
exactly	O
the	O
fraction	O
of	O
the	O
server	O
given	O
by	O
the	O
formula	O
above	O
.	O
</s>
<s>
Therefore	O
,	O
GPS	O
is	O
mostly	O
a	O
theoretical	O
idea	O
,	O
and	O
several	O
scheduling	O
algorithms	O
have	O
been	O
developed	O
to	O
approximate	O
this	O
GPS	O
ideal	O
:	O
PGPS	O
,	O
aka	O
Weighted	B-Algorithm
fair	I-Algorithm
queuing	I-Algorithm
,	O
is	O
the	O
most	O
known	O
implementation	O
of	O
GPS	O
,	O
but	O
it	O
has	O
some	O
drawbacks	O
,	O
and	O
several	O
other	O
implementations	O
have	O
been	O
proposed	O
,	O
as	O
Deficit	B-Algorithm
round	I-Algorithm
robin	I-Algorithm
or	O
WF2Q	O
.	O
</s>
<s>
GPS	O
is	O
considered	O
as	O
a	O
fair	O
ideal	O
,	O
and	O
all	O
its	O
approximations	O
"	O
use	O
it	O
as	O
a	O
reference	O
to	O
measure	O
fairness.	O
"	O
</s>
<s>
Nevertheless	O
,	O
several	O
Fairness	B-Protocol
measures	I-Protocol
exist	O
.	O
</s>
