<s>
Microarchitecture	B-Application
simulation	I-Application
is	O
an	O
important	O
technique	O
in	O
computer	B-General_Concept
architecture	I-General_Concept
research	O
and	O
computer	B-General_Concept
science	I-General_Concept
education	O
.	O
</s>
<s>
It	O
is	O
a	O
tool	O
for	O
modeling	O
the	O
design	O
and	O
behavior	O
of	O
a	O
microprocessor	B-Architecture
and	O
its	O
components	O
,	O
such	O
as	O
the	O
ALU	B-General_Concept
,	O
cache	B-General_Concept
memory	I-General_Concept
,	O
control	B-General_Concept
unit	I-General_Concept
,	O
and	O
data	O
path	O
,	O
among	O
others	O
.	O
</s>
<s>
The	O
simulation	O
allows	O
researchers	O
to	O
explore	O
the	O
design	O
space	O
as	O
well	O
as	O
to	O
evaluate	O
the	O
performance	O
and	O
efficiency	O
of	O
novel	O
microarchitecture	B-General_Concept
features	O
.	O
</s>
<s>
For	O
example	O
,	O
several	O
microarchitecture	B-General_Concept
components	O
,	O
such	O
as	O
branch	B-General_Concept
predictors	I-General_Concept
,	O
re-order	B-General_Concept
buffer	I-General_Concept
,	O
and	O
trace	B-General_Concept
cache	I-General_Concept
,	O
went	O
through	O
numerous	O
simulation	O
cycles	O
before	O
they	O
become	O
common	O
components	O
in	O
contemporary	O
microprocessors	B-Architecture
of	O
today	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
simulation	O
also	O
enables	O
educators	O
to	O
teach	O
computer	B-General_Concept
organization	I-General_Concept
and	O
architecture	O
courses	O
with	O
hand-on	O
experiences	O
.	O
</s>
<s>
For	O
system-level	O
simulation	O
of	O
computer	O
hardware	O
,	O
please	O
refer	O
to	O
the	O
full	B-Application
system	I-Application
simulation	I-Application
.	O
</s>
<s>
Microarchitecture	B-Application
simulation	I-Application
can	O
be	O
classified	O
into	O
multiple	O
categories	O
according	O
to	O
input	O
types	O
and	O
level	O
of	O
details	O
.	O
</s>
<s>
Specifically	O
,	O
the	O
input	O
can	O
be	O
a	O
trace	O
collected	O
from	O
an	O
execution	O
of	O
program	O
on	O
a	O
real	O
microprocessor	B-Architecture
(	O
so	O
called	O
trace-driven	O
simulation	O
)	O
or	O
a	O
program	O
itself	O
(	O
so	O
called	O
execution-driven	O
simulation	O
)	O
.	O
</s>
<s>
However	O
,	O
the	O
execution-driven	O
simulation	O
is	O
much	O
slower	O
than	O
the	O
trace-driven	O
simulation	O
because	O
it	O
has	O
to	O
process	O
each	O
instruction	O
one-by-one	O
and	O
update	O
all	O
statuses	O
of	O
the	O
microarchitecture	B-General_Concept
components	O
involved	O
.	O
</s>
<s>
In	O
particular	O
,	O
a	O
piece	O
of	O
software	O
that	O
simulates	O
a	O
microprocessor	B-Architecture
executing	O
a	O
program	O
on	O
a	O
cycle-by-cycle	O
basis	O
is	O
known	O
as	O
cycle-accurate	B-Application
simulator	I-Application
,	O
whereas	O
instruction	B-Application
set	I-Application
simulator	I-Application
only	O
models	O
the	O
execution	O
of	O
a	O
program	O
on	O
a	O
microprocessor	B-Architecture
through	O
the	O
eyes	O
of	O
an	O
instruction	O
scheduler	O
along	O
with	O
a	O
coarse	O
timing	O
of	O
instruction	O
execution	O
.	O
</s>
<s>
Most	O
computer	B-General_Concept
science	I-General_Concept
classes	O
in	O
computer	B-General_Concept
architecture	I-General_Concept
with	O
hand-on	O
experiences	O
adopt	O
the	O
instruction	B-Application
set	I-Application
simulators	I-Application
as	O
tools	O
for	O
teaching	O
,	O
whereas	O
the	O
cycle-accurate	B-Application
simulators	I-Application
are	O
deployed	O
mostly	O
for	O
research	O
projects	O
due	O
to	O
both	O
complexities	O
and	O
resource	O
consumption	O
.	O
</s>
<s>
Microarchitecture	B-General_Concept
simulators	O
are	O
deployed	O
for	O
a	O
variety	O
of	O
purposes	O
.	O
</s>
<s>
It	O
allows	O
researchers	O
to	O
evaluate	O
their	O
ideas	O
without	O
the	O
need	O
to	O
fabricate	O
a	O
real	O
microprocessor	B-Architecture
chip	O
,	O
which	O
is	O
both	O
expensive	O
and	O
time	O
consuming	O
.	O
</s>
<s>
For	O
instance	O
,	O
simulating	O
a	O
microprocessor	B-Architecture
with	O
thousand	O
of	O
cores	O
along	O
with	O
multiple	O
levels	O
of	O
cache	B-General_Concept
memory	I-General_Concept
incurs	O
very	O
little	O
cost	O
when	O
comparing	O
with	O
the	O
fabrication	O
of	O
a	O
prototyping	O
chip	O
.	O
</s>
<s>
Another	O
usage	O
of	O
the	O
microarchitecture	B-General_Concept
simulator	O
is	O
in	O
education	O
.	O
</s>
<s>
Given	O
that	O
a	O
course	O
in	O
computer	B-General_Concept
architecture	I-General_Concept
teaches	O
students	O
many	O
different	O
microprocessor	B-Architecture
's	O
features	O
and	O
its	O
architectures	O
,	O
the	O
microarchitecture	B-General_Concept
simulator	O
is	O
ideal	O
for	O
modeling	O
and	O
experimenting	O
with	O
different	O
features	O
and	O
architectures	O
over	O
the	O
course	O
of	O
a	O
semester	O
.	O
</s>
<s>
For	O
example	O
,	O
students	O
may	O
start	O
with	O
a	O
microarchitecture	B-General_Concept
simulator	O
that	O
models	O
a	O
simple	O
microprocessor	B-Architecture
design	O
at	O
the	O
beginning	O
of	O
a	O
semester	O
.	O
</s>
<s>
As	O
the	O
semester	O
progresses	O
,	O
additional	O
features	O
,	O
such	O
as	O
instruction	B-General_Concept
pipelining	I-General_Concept
,	O
register	B-Architecture
renaming	I-Architecture
,	O
reservation	B-General_Concept
stations	I-General_Concept
,	O
out-of-order	B-General_Concept
execution	I-General_Concept
,	O
and	O
scoreboarding	B-General_Concept
,	O
can	O
be	O
modeled	O
and	O
added	O
to	O
the	O
simulator	O
as	O
they	O
are	O
introduced	O
in	O
the	O
classroom	O
.	O
</s>
<s>
Microarchitecture	B-General_Concept
simulator	O
provides	O
the	O
flexibility	O
of	O
reconfiguration	O
and	O
testing	O
with	O
minimal	O
costs	O
.	O
</s>
