<s>
The	O
term	O
scheduling	B-Algorithm
analysis	O
in	O
real-time	B-General_Concept
computing	I-General_Concept
includes	O
the	O
analysis	O
and	O
testing	O
of	O
the	O
scheduler	B-Algorithm
system	O
and	O
the	O
algorithms	O
used	O
in	O
real-time	B-General_Concept
applications	I-General_Concept
.	O
</s>
<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
real-time	O
scheduling	B-Algorithm
analysis	O
is	O
the	O
evaluation	O
,	O
testing	O
and	O
verification	O
of	O
the	O
scheduling	B-Operating_System
system	I-Operating_System
and	O
the	O
algorithms	O
used	O
in	O
real-time	O
operations	O
.	O
</s>
<s>
For	O
critical	O
operations	O
,	O
a	O
real-time	B-General_Concept
system	I-General_Concept
must	O
be	O
tested	O
and	O
verified	O
for	O
performance	O
.	O
</s>
<s>
A	O
real-time	O
scheduling	B-Operating_System
system	I-Operating_System
is	O
composed	O
of	O
the	O
scheduler	B-Algorithm
,	O
clock	O
and	O
the	O
processing	O
hardware	O
elements	O
.	O
</s>
<s>
In	O
a	O
real-time	B-General_Concept
system	I-General_Concept
,	O
a	O
process	O
or	O
task	O
has	O
schedulability	B-Algorithm
;	O
tasks	O
are	O
accepted	O
by	O
a	O
real-time	B-General_Concept
system	I-General_Concept
and	O
completed	O
as	O
specified	O
by	O
the	O
task	O
deadline	O
depending	O
on	O
the	O
characteristic	O
of	O
the	O
scheduling	B-Algorithm
algorithm	O
.	O
</s>
<s>
Modeling	O
and	O
evaluation	O
of	O
a	O
real-time	O
scheduling	B-Operating_System
system	I-Operating_System
concern	O
is	O
on	O
the	O
analysis	O
of	O
the	O
algorithm	O
capability	O
to	O
meet	O
a	O
process	O
deadline	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
a	O
real-time	O
scheduling	B-Algorithm
algorithm	O
a	O
deadline	O
could	O
be	O
set	O
to	O
five	O
nano-seconds	O
.	O
</s>
<s>
A	O
task	O
in	O
a	O
real-time	B-General_Concept
system	I-General_Concept
must	O
be	O
completed	O
“	O
neither	O
too	O
early	O
nor	O
too	O
late	O
;	O
..	O
”	O
.	O
</s>
<s>
The	O
criteria	O
of	O
a	O
real-time	O
can	O
be	O
classified	O
as	O
hard	B-General_Concept
,	O
firm	B-General_Concept
or	O
soft	B-General_Concept
.	O
</s>
<s>
The	O
scheduler	B-Algorithm
set	O
the	O
algorithms	O
for	O
executing	O
tasks	O
according	O
to	O
a	O
specified	O
order	O
.	O
</s>
<s>
There	O
are	O
multiple	O
mathematical	O
models	O
to	O
represent	O
a	O
scheduling	B-Operating_System
System	I-Operating_System
,	O
most	O
implementations	O
of	O
real-time	O
scheduling	B-Algorithm
algorithm	O
are	O
modeled	O
for	O
the	O
implementation	O
of	O
uniprocessors	O
or	O
multiprocessors	O
configurations	O
.	O
</s>
<s>
The	O
more	O
challenging	O
scheduling	B-Algorithm
algorithm	O
is	O
found	O
in	O
multiprocessors	O
,	O
it	O
is	O
not	O
always	O
feasible	O
to	O
implement	O
a	O
uniprocessor	O
scheduling	B-Algorithm
algorithm	O
in	O
a	O
multiprocessor	O
.	O
</s>
<s>
The	O
algorithms	O
used	O
in	O
scheduling	B-Algorithm
analysis	O
“	O
can	O
be	O
classified	O
as	O
pre-emptive	O
or	O
non-pre-emptive	B-Operating_System
"	I-Operating_System
.	O
</s>
<s>
A	O
scheduling	B-Algorithm
algorithm	O
defines	O
how	O
tasks	O
are	O
processed	O
by	O
the	O
scheduling	B-Operating_System
system	I-Operating_System
.	O
</s>
<s>
In	O
general	O
terms	O
,	O
in	O
the	O
algorithm	O
for	O
a	O
real-time	O
scheduling	B-Operating_System
system	I-Operating_System
,	O
each	O
task	O
is	O
assigned	O
a	O
description	O
,	O
deadline	O
and	O
an	O
identifier	O
(	O
indicating	O
priority	O
)	O
.	O
</s>
<s>
The	O
selected	O
scheduling	B-Algorithm
algorithm	O
determines	O
how	O
priorities	O
are	O
assigned	O
to	O
a	O
particular	O
task	O
.	O
</s>
<s>
A	O
real-time	O
scheduling	B-Algorithm
algorithm	O
can	O
be	O
classified	O
as	O
static	O
or	O
dynamic	O
.	O
</s>
<s>
For	O
a	O
static	O
scheduler	B-Algorithm
,	O
task	O
priorities	O
are	O
determined	O
before	O
the	O
system	O
runs	O
.	O
</s>
<s>
A	O
dynamic	O
scheduler	B-Algorithm
determines	O
task	O
priorities	O
as	O
it	O
runs	O
.	O
</s>
<s>
Tasks	O
are	O
accepted	O
by	O
the	O
hardware	O
elements	O
in	O
a	O
real-time	O
scheduling	B-Operating_System
system	I-Operating_System
from	O
the	O
computing	O
environment	O
and	O
processed	O
in	O
real-time	O
.	O
</s>
<s>
It	O
is	O
not	O
always	O
possible	O
to	O
meet	O
the	O
required	O
deadline	O
;	O
hence	O
further	O
verification	O
of	O
the	O
scheduling	B-Algorithm
algorithm	O
must	O
be	O
conducted	O
.	O
</s>
<s>
Two	O
different	O
models	O
can	O
be	O
implemented	O
using	O
a	O
dynamic	O
scheduling	B-Algorithm
algorithm	O
;	O
a	O
task	O
deadline	O
can	O
be	O
assigned	O
according	O
to	O
the	O
task	O
priority	O
(	O
earliest	O
deadline	O
)	O
or	O
a	O
completion	O
time	O
for	O
each	O
task	O
is	O
assigned	O
by	O
subtracting	O
the	O
processing	O
time	O
from	O
the	O
deadline	O
(	O
least	O
laxity	O
)	O
.	O
</s>
<s>
The	O
performance	O
verification	O
and	O
execution	O
of	O
a	O
real-time	O
scheduling	B-Algorithm
algorithm	O
is	O
performed	O
by	O
the	O
analysis	O
of	O
the	O
algorithm	O
execution	O
times	O
.	O
</s>
<s>
Verification	O
for	O
the	O
performance	O
of	O
a	O
real-time	O
scheduler	B-Algorithm
will	O
require	O
testing	O
the	O
scheduling	B-Algorithm
algorithm	O
under	O
different	O
test	O
scenarios	O
including	O
the	O
worst-case	B-General_Concept
execution	I-General_Concept
time	I-General_Concept
.	O
</s>
<s>
The	O
time	O
calculations	O
required	O
for	O
the	O
analysis	O
of	O
scheduling	B-Algorithm
systems	O
require	O
evaluating	O
the	O
algorithm	O
at	O
the	O
code	O
level	O
.	O
</s>
<s>
Different	O
methods	O
can	O
be	O
applied	O
to	O
testing	O
a	O
scheduling	B-Operating_System
System	I-Operating_System
in	O
a	O
real-time	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Retesting	O
requirements	O
after	O
changes	O
to	O
the	O
scheduling	B-Operating_System
System	I-Operating_System
are	O
considered	O
in	O
a	O
case	O
by	O
case	O
basis	O
.	O
</s>
<s>
Testing	O
and	O
verification	O
of	O
real-time	B-General_Concept
systems	I-General_Concept
should	O
not	O
be	O
limited	O
to	O
input/output	O
and	O
codes	O
verifications	O
but	O
are	O
performed	O
also	O
in	O
running	O
applications	O
using	O
intrusive	O
or	O
non-intrusive	O
methods	O
.	O
</s>
