On Mon, Sep 13, 2021, at 1:01 PM, Sohil Mehta wrote: > Add a new system call to allow applications to block in the kernel and > wait for user interrupts. > ... > > When the application makes this syscall the notification vector is > switched to a new kernel vector. Any new SENDUIPI will invoke the kernel > interrupt which is then used to wake up the process. Any new SENDUIPI that happens to hit the target CPU's ucode at a time when the kernel vector is enabled will deliver the interrupt. Any new SENDUIPI that happens to hit the target CPU's ucode at a time when a different UIPI-using task is running will *not* deliver the interrupt, unless I'm missing some magic. Which means that wakeups will be missed, which I think makes this whole idea a nonstarter. Am I missing something?
