On 2/23/21 12:49 PM, Will Deacon wrote: >>> I totally agree on this point. In the case of runtime switching we might >>> need >>> the rethink completely the strategy and depends a lot on what we want to >>> allow >>> and what not. For the kernel I imagine we will need to expose something in >>> sysfs >>> that affects all the cores and then maybe stop_machine() to propagate it to >>> all >>> the cores. Do you think having some of the cores running in sync mode and >>> some >>> in async is a viable solution? >> stop_machine() is an option indeed. I think it's still possible to run >> some cores in async while others in sync but the static key here would >> only be toggled when no async CPUs are left. > Just as a general point, but if we expose stop_machine() via sysfs we > probably want to limit that to privileged users so you can't DoS the system > by spamming into the file.
I agree, if we ever introduce the runtime switching and go for this option we should make sure that we do it safely. -- Regards, Vincenzo
