On Thu, 2020-07-23 at 16:29 +0200, Peter Zijlstra wrote: > . > > This.. as presented it is an absolutely unreviewable pile of junk. It > presents code witout any coherent problem description and analysis. > And > the patches are not split sanely either. There is a more complete and slightly outdated description in the previous version of the patch at https://lore.kernel.org/lkml/07c25c246c55012981ec0296eee23e68c719333a.camel@xxxxxxxxxxx/ . It allows userspace application to take a CPU core for itself and run completely isolated, with no disturbances. There is work in progress that also disables and re-enables TLB flushes, and depending on CPU it may be possible to also pre-allocate cache, so it would not be affected by the rest of the system. Events that cause interaction with isolated task, cause isolation breaking, turning the task into a regular userspace task that can continue running normally and enter isolated state again if necessary. To make this feature suitable for any practical use, many mechanisms that normally would cause events on a CPU, should exclude CPU cores in this state, and synchronization should happen later, at the time of isolation breaking. There are three architectures supported, x86, arm and arm64, and it should be possible to extend it to others. Unfortunately kernel entry procedures are neither unified, nor straightforward, so introducing new feature to them causes an appearance of a mess. -- Alex
