On Mon, Apr 20, 2020 at 9:31 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > Hi Steve, > > > > > Won't that while loop just go into a spin? > > > > > > What about something like a fsnotify on a /proc/<pid>/ file? > > > > > > I rather have trace-cmd sleep and wake up when a task exits, than to do a > > > spin. Like it does for the -F option. > > > > I just tried doing this using the inotify API and hit a snag. > > It turns out inotify can't monitor pseudo-filesystems like /proc, so I > > don't think that suggestion will work. > > > > What if I put a call to sleep in the loop? > > It's not the most elegant solution, but that way it wouldn't be too > > different from the current code that sleeps for 10 seconds after > > checking if finished is set to true. > > Perhaps using the new pidfd interface may work here. > > https://lwn.net/Articles/794707/ > > It was added in 5.4 (which is still rather new), but this would be a > new trace-cmd feature as well. > > -- Steve > This is a stupid question, but what would be the best way to use the pidfd interface and also keep backwards compatibility with older kernel versions? Or is that not really a concern? Bijan
|