STREAMS/UX for the HP 9000 Reference Manual

STREAMS/UX Multiprocessor Support

Porting SVR4 MP Modules and Drivers to HP-UX

Strategies for Porting SVR4 MP Modules and Drivers to HP-UX

The best way to port SVR4 MP scalable modules and drivers to HP-UX is to

change the SVR4 MP code to use the STREAMS/UX synchronization

levels. First, analyze how the SVR4 MP code shares data structures, and

then conﬁgure the modules and drivers to use synchronization levels which

correctly serialize access to shared data. You can use deﬁnes to change

module and driver spinlock calls to no-ops. This approach is likely to get the

best performance, but may require much effort. Also, the STREAMS/UX

synchronization levels may not be suitable for all designs.

To make porting easier, STREAMS/UX will provide support for the SVR4

MP spinlock primitives. SVR4 MP modules and drivers could be ported to

HP-UX by conﬁguring them to run with queue synchronization and leaving

in the calls to SVR4 MP spinlock routines. A disadvantage of this porting

strategy is that it may not achieve as much performance as the ﬁrst. Some of

the synchronization provided by STREAMS/UX will be redundant with the

synchronization implemented by module and driver spinlocks. In some

cases, a combination of these two strategies may make sense. For example,

suppose several modules and drivers share the same structure, but do not

access it on the main read and write paths. You can use SVR4 MP spinlocks

to protect this data, but use the STREAMS/UX synchronization levels to

protect other structures.