On Wed, 13 Jan 2021, Marcelo Tosatti wrote:

So as discussed, this is one possible prctl interface for
task isolation.

Is this something that is desired? If not, what is the
proper way for the interface to be?

Sure that sounds liek a good beginning but I guess we need some
specificity on the features

+Task isolation CPU interface
+============================

How does one do a oneshot flush of OS activities?

I.e. I have a polling loop over numerous shared and I/o devices in user
space and I want to make sure that the system is quite before I enter the
loop. In the loop itself some activities may require syscalls so they will
potentialy cause the OS services such as timers to start again. When such
an activities is complete another quiet down call can be issued.

Could be implemented by setting a flag that does an action and then resets
itself?  Or the flag could be reset if a syscall that requires timers etc
is used?

Features that I think may be needed:

F_ISOL_QUIESCE		-> quiet down now but allow all OS activities. OS
			activites reset flag

F_ISOL_BAREMETAL_HARD	-> No OS interruptions. Fault on syscalls that
			require such actions in the future.

F_ISOL_BAREMETAL_WARN	-> Similar. Create a warning in the syslog when OS
				services require delayed processing etc
				but continue while resetting the flag.