STREAMS/UX for the HP 9000 Reference Manual

STREAMS/UX Multiprocessor Support

Writing MP Scalable Modules and Drivers

Overview of STREAMS/UX MP Support

HP-UX STREAMS supports MP scalable drivers and modules. You can

conﬁgure the amount of parallelism for modules and drivers. Pick a level

which is consistent with a module's or driver's use of shared data structures.

STREAMS/UX provides ﬁve levels of parallelism which are called queue,

queue pair, module, elsewhere, and global. They are described below. Also,

STREAMS provides extra synchronization for module and driver open and

close functions. This synchronization is also described below. The term

module is used in this discussion to mean both modules and drivers, unless

otherwise stated.

Figure 1 is useful for understanding STREAMS/UX MP support. The

diagram shows four streams, ECHO-A, ECHO-B, DLPI-A and SAD-A.

ECHO-A and ECHO-B both contain the echo driver. DLPI-A contains dlpi,

and SAD-A has sad. Each driver contains a read and a write queue.

echo_rput and echo_rsrv operate on an echo driver's read queue. echo_wput

and echo_wsrv access the write queue. The dlpi and sad driver functions are

similar to the echo driver functions. STREAMS/UX executes echo, dlpi,

and sad driver functions differently depending on the MP synchronization

level conﬁgured for the drivers.