User manual

Interprocessor Synchronization Window
52
Valid combinations of these parameters are:
INTERLOCK = PORTABLE
SYNCW = NONE, TIME_CONTROL = 6
This is the default setting.
Synchronization window is not used.
This setting provides the best scalability in portable
mode.
It is safe with base OpenVMS, but may potentially
cause OpenVMS to crash under some code
sequences that do not exist in base OpenVMS but
might exist in layered or third-party privileged
products.
INTERLOCK=PORTABLE
SYNCW = ILK, TIME_CONTROL = 6
SYNCW = SYS, TIME_CONTROL = 2 or 6
SYNCW = (SYS,ILK), TIME_CONTROL = 2 or 6
These are the safest settings.
These settings engage one or both components of
synchronization window.
They may slightly reduce scalability and
performance compared to the default setting.
Use these settings only when running layered or
third-party privileged components that are known to
crash for SMP-timing related reasons (such as
bugchecks CPUSPINWAIT or BADQHDR) under the
default configurations. Currently no such
components are known.
INTERLOCK=NATIVE
SYNCW = ILK, TIME_CONTROL = 6
SYNCW = (SYS, ILK), TIME_CONTROL = 2 or 6
Using native mode.
When using native mode, ILK is a must.
Native mode is experimental at this point and only
limited testing had been performed for it.
Native mode is expected to offer less overhead than
portable mode when system makes heavy use of
BBSSI and BBCCI interlocked instructions, such as
heavily using spinlocks, which in turn may occur
during heavy paging or intense IO.
Actual performance benefits of native mode have
not been assessed yet. Native mode may be faster
than portable mode on some workloads.