<s>
In	O
systems	O
as	O
Multiprocessor	O
system	O
,	O
multi-core	B-Architecture
and	O
NUMA	B-Operating_System
system	I-Operating_System
,	O
where	O
a	O
dedicated	O
cache	O
for	O
each	O
processor	O
,	O
core	O
or	O
node	O
is	O
used	O
,	O
a	O
consistency	O
problem	O
may	O
occur	O
when	O
a	O
same	O
data	O
is	O
stored	O
in	O
more	O
than	O
one	O
cache	O
.	O
</s>
<s>
The	O
connection	O
is	O
made	O
using	O
a	O
System	B-Architecture
Bus	I-Architecture
or	O
a	O
Crossbar	O
(	O
"	O
xbar	O
"	O
)	O
or	O
a	O
mix	O
of	O
two	O
previously	O
approach	O
,	O
bus	O
for	O
address	O
and	O
crossbar	O
for	O
Data	O
(	O
Data	O
crossbar	O
)	O
.	O
</s>
<s>
Bandwidth	O
can	O
be	O
increasing	O
by	O
using	O
large	O
data	O
bus	O
path	O
,	O
data	O
crossbar	O
,	O
memory	B-General_Concept
interleaving	I-General_Concept
(	O
multi-bank	O
parallel	O
access	O
)	O
and	O
out	B-General_Concept
of	I-General_Concept
order	I-General_Concept
data	O
transaction	O
.	O
</s>
<s>
Usually	O
in	O
SMP	O
the	O
coherency	O
is	O
based	O
on	O
the	O
"	O
Bus	O
watching	O
"	O
or	O
"	O
Snoopy	B-Application
"	O
(	O
after	O
the	O
Peanuts	O
 '	O
character	O
Snoopy	B-Application
)	O
approach	O
.	O
</s>
<s>
Protocols	O
SI	O
protocol	O
Write	O
Through	O
MSI	O
protocol	O
Synapse	O
protocol	O
MEI	O
protocol	O
IBM	O
PowerPC	B-Device
750	I-Device
,	O
MPC750UM/D	O
12/2001	O
Rev	O
.	O
</s>
<s>
160	O
–	O
Di	O
T	O
.	O
Shanley	O
–	O
https://books.google.com/books?id=MLJClvCYh34C&dq=Pentium+protocol+cache&pg=PA160	O
PowerPC	O
,	O
Intel	O
Harpertown	O
(	O
Xeon	O
5400	O
)	O
MOSI	O
protocol	O
Berkeley	O
protocol	O
MOESI	O
protocol	O
AMD64	B-Device
,	O
AMD64	B-Device
Technology	O
–	O
AMD64	B-Device
Architecture	O
Programmer	O
's	O
Manual	O
Volume	O
2	O
:	O
System	O
Programming	O
–	O
http://developer.amd.com/wordpress/media/2012/10/24593_APM_v21.pdf	O
MOESI	O
,	O
Sweazey	O
,	O
P.	O
,	O
and	O
Smith	O
,	O
A	O
.	O
J	O
.	O
</s>
<s>
AMD64	B-Device
,	O
Bull	O
HN	O
ISI	O
–	O
see	O
"	O
Read	O
Miss	O
"	O
operation	O
below	O
)	O
.	O
</s>
<s>
AMD64	B-Device
)	O
–	O
The	O
requesting	O
cache	O
is	O
set	O
S	O
(	O
V	O
)	O
,	O
or	O
R/F	O
in	O
R-MESI	O
type	O
/	O
MESIF	O
protocols	O
and	O
E	O
(	O
R	O
)	O
cache	O
is	O
changed	O
in	O
S	O
(	O
V	O
)	O
or	O
in	O
I	O
in	O
MEI	O
protocol	O
.	O
</s>
<s>
Note	O
:	O
Cache-to-cache	O
is	O
an	O
efficient	O
approach	O
in	O
multiprocessor/multicore	O
systems	O
direct	O
connected	O
between	O
them	O
,	O
but	O
less	O
in	O
Remote	O
cache	O
as	O
in	O
NUMA	O
systems	O
where	O
a	O
standard	O
MESI	O
is	O
preferable	O
.	O
</s>
