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iAPX
432
Interface
Processor
Architecture
Reference
Manual
2-4.
FACILITIES
FUR
ASYNCHRCNOUS
CDMJNlCATICN
The IP
offers
the
same
set
of
operators
for
asynchronous
interprocess
communication
as
does
a
GOP,
with
the
excey;>tion
that
the
DEIAY
operator
ls
not
implemented. The DEIAY
operator,
used
in
scheduling
to
delay
a
process
from
being
dispatched
(on a GOP),
is
not
required
by
an
IP
where
process
scheduling
and
dispatching
is
per
formed
by
the
I/O
oontroller.
2-5.
POOCESSES
AND
LOCAL
STORAGE
RESOURCE
MANAGEMENT
The
IP
performs
no
process
scheduling
or
local
storage
resource
management.
Multiple
IP
process
objects
may
coexist
in
432 memory.
I/O
oontroller
software
nust
select
a
process
envi
rornnent
in
which
an
IP
function
is
to
be
performed.
Unlike
the
GOP,
where a
process
may
be composed
of
nultiple
contexts,
an
IP
process
is
bound
to
a
sing
Ie
context
dur
ing
its
lifetime.
In
fact,
the
context
is
a
refinement
of
an
IP
process
object.
Further,
since
no
local
storage
management j.s
performed
by
an
IP,
the
size
of
a
process's
context
is
static
over
the
life
of
the
process.
2-6.
PRCX:ESS
SCHEOOLING
AND
DISPA'lCHING
Generally,
software
in
the
I/O
controller
is
responsible
for
all
IP
process
scheduling
and
dispatching.
A
process
is
selected
and bound
to
an
IP
processor
object
when
an
IP
function
is
invoked.
The
process
selection
index
field
in
the
IP's
function
request
facility
specifies
which
process
is
to
be
selected.
Since
the
IP
is
not
self-dispatching,
a
strategy
routine
in
the
I/O
controller
has
responsi.bility
for
multiplexing
the
various
IP
processes
over
time.
The
IP
does
not
maintain
a
process
clock.
Process
time
management
is
performed
by
the
I/O
controller.
Consistent
with
432
philosophy,
the
IP
provides
the
mechanisms
for
process
scheduling
and
dispatching
but
the
PQlicy
for
deployment
is
totally
under
the
direction
of
I/O
controller
software.
2-7.
F1-\CILITIES
FOR
0BJEC1'
MANAGEMENT
The
IP
provides
a
spectrum
of
facilities
which
may
be
used
for
securely
managing
obj
ects:
communications
ports,
I/O
locks,
and
indivi.sible
short
ordinal
operations.
The
IP
offers
the
same
asynchronous
communication
port
mechanisms
as
a
GOP.
Canmun
icat
ions
ports
may
be
used
by
processes
to
asynchronously
send
and
receive
messages
(objects).
2-8