On Tue, 28 Jan 2025 13:38:42 -1000 Tejun Heo <tj@xxxxxxxxxx> wrote: > On Tue, Jan 28, 2025 at 06:29:57PM -0500, Steven Rostedt wrote: > > What I did for eventfs, and what I believe kernfs does, is to create a > > small descriptor to represent the control data and reference them like what > > you would have on disk. That is, the control elements (like an trace event > > descriptor) is really what is on "disk". When someone does an "ls" to the > > pseudo file system, there needs to be a way for the VFS layer to query the > > control structures like how a normal file system would query that data > > stored on disk, and then let the VFS layer create the dentry and inodes > > when referenced, and more importantly, free them when they are no longer > > referenced and there's memory pressure. > > Yeap, that's exactly what kernfs does. And eventfs goes one step further. Because there's a full directory layout that's identical for every event, it has a single descriptor for directory and not for file. As there can be over 10 files per directory/event I didn't want to waste even that memory. This is why I couldn't use kernfs for eventfs, as I was able to still save a couple of megabytes by not having the files have any descriptor representing them (besides a single array for all events). -- Steve
