Page 87 - slides.dvi

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3.
2.
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Most
From
Operating
.
.
systems
.
can
I/O
the
easy
most
behaviour:
Systems
Blocking
be
Blocking:
returns
to
—
but
(e.g.
systems
v.
I/O
essentially
Nonblocking:
insufficient
use
used
Asynchronous:
also
NT,
flexible
for
almost
subsystem
by
process
I/O
and
provide
Subsystem
most
(and
programmer’s
e.g.
call
Linux)
some
process
both
explicitly
user
point
also
difficult
suspended
Nonblocking
application-level
of
needs.
immediately
returns
understand.
to
potentially
as
continues
blocking
until
signals
with
I/O
support
view,
to
use.
interface
“polled
and
I/O
much
I/O
run
count
as
efficient).
process
code.
I/O”.
of
while
system
when
asynchronous
completed
bytes
I/O
available
its
non-blocking
calls
I/O,
read
I/O
I/O
or
but
executes
exhibit
used
request
one
written
interfaces;
of
has
three
modern
(possibly
infrequently.
kinds
0).
completed.
of
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