On Wed, 29 Nov 2023 00:17:38 +0900 Masami Hiramatsu (Google) <mhira...@kernel.org> wrote:
> Hi Steve, > > On Mon, 27 Nov 2023 17:41:08 -0500 > Steven Rostedt <rost...@goodmis.org> wrote: > > > From: "Steven Rostedt (Google)" <rost...@goodmis.org> > > > > A trace instance may only need to enable specific events. As the eventfs > > directory of an instance currently creates all events which adds overhead, > > allow internal instances to be created with just the events in systems > > that they care about. This currently only deals with systems and not > > individual events, but this should bring down the overhead of creating > > instances for specific use cases quite bit. > > This sounds good, but can the eventfs reduce such overhead because > if the user doesn't touch the actual event, the event dentry will > be released soon? Yes, but this also removes the creation of the meta data behind it. Which has a descriptor for every event. And since there are over a thousand events, this is still quite a bit of savings. It also removes the eventfs_inode that represents each directory. > > Note, this may also be useful for creating instances in the eventfs, but > > I'm not sure how to do this there. I could add a deliminator: > > > > mkdir /sys/kernel/tracing/instances/foo::sched,timer > > Can we limit this after making an instance? In that case, we can use > rmdir to remove unused "systems" directories. Or, maybe we can create > it afterwards with mkdir or use comand to a pseudo file. > > echo sched:* timer:* > instances/foo/available_events That, or I even thought of allowing rmdir on event systems, and even mkdir. # cd instance/foo/events # rmdir * # mkdir sched timer -- Steve
