On 5/20/21 12:33 PM, Quentin Perret wrote: > On Thursday 20 May 2021 at 11:16:41 (+0100), Will Deacon wrote: >> Ok, thanks for the insight. In which case, I'll go with what we discussed: >> require admission control to be disabled for sched_setattr() but allow >> execve() to a 32-bit task from a 64-bit deadline task with a warning (this >> is probably similar to CPU hotplug?). > > Still not sure that we can let execve go through ... It will break AC > all the same, so it should probably fail as well if AC is on IMO > If the cpumask of the 32-bit task is != of the 64-bit task that is executing it, the admission control needs to be re-executed, and it could fail. So I see this operation equivalent to sched_setaffinity(). This will likely be true for future schedulers that will allow arbitrary affinities (AC should run on affinity change, and could fail). I would vote with Juri: "I'd go with fail hard if AC is on, let it pass if AC is off (supposedly the user knows what to do)," (also hope nobody complains until we add better support for affinity, and use this as a motivation to get back on this front). -- Daniel
