On Wed, Mar 31, 2021 at 07:16:45PM -0700, Manish Varma wrote: > timerfd doesn't create any wakelocks, but eventpoll can. When it does, > it names them after the underlying file descriptor, and since all > timerfd file descriptors are named "[timerfd]" (which saves memory on > systems like desktops with potentially many timerfd instances), all > wakesources created as a result of using the eventpoll-on-timerfd idiom > are called... "[timerfd]". > > However, it becomes impossible to tell which "[timerfd]" wakesource is > affliated with which process and hence troubleshooting is difficult. > > This change addresses this problem by changing the way eventpoll > wakesources are named: > > 1) the top-level per-process eventpoll wakesource is now named "epoll:P" > (instead of just "eventpoll"), where P, is the PID of the creating > process. > 2) individual per-underlying-filedescriptor eventpoll wakesources are > now named "epollitemN:P.F", where N is a unique ID token and P is PID > of the creating process and F is the name of the underlying file > descriptor. > > All together that should be splitted up into a change to eventpoll and > timerfd (or other file descriptors). FWIW, it smells like a variant of wakeup_source_register() that would take printf format + arguments would be a good idea. I.e. something like > + snprintf(buf, sizeof(buf), "epoll:%d", task_pid); > + epi->ep->ws = wakeup_source_register(NULL, buf); ... = wakeup_source_register(NULL, "epoll:%d", task_pid); etc.
