Page 65 - slides.dvi

•
•
•
–
–
–
–
–
–
If
–
Operating
∗
∗
if
if
no
to
to
Often
can
store
i.e.
Popular
Systems
before
reset
h/w
—
clear
use
check
give
if
Page
NRU
reference
pages
it
referenced
Approximating
in
bit
similar
“a
⇒
provided
reference
implemented
is
discarding
“reference
Replacement
scheme:
0,
queue
LRU
bit,
trap,
with
referenced,
scheme
second
head,
as
bit”,
then
and
Algorithms
to
(2)
reference
per
check
update
check
bit
mark
add
circular
chance”
discard
its
FIFO
can
emulate
PTE,
second-chance
page
page
it,
queue
to
no
and
permissions
FIFO
and
tail
reference
emulate:
modified
of
access
bit
otherwise:
head
resume
bit
queue
pointer:
then
called
clock.
61