On Wed, May 03, 2023 at 08:19:24AM -1000, Tejun Heo wrote:

quoted

Taking a step back though, given the multitude of allocation sites in
the kernel, it's a bit odd that the only accounting we do is the tiny
fraction of voluntary vmstat/meminfo reporting. We try to cover the
biggest consumers with this of course, but it's always going to be
incomplete and is maintenance overhead too. There are on average
several gigabytes in unknown memory (total - known vmstats) on our
machines. It's difficult to detect regressions easily. And it's per
definition the unexpected cornercases that are the trickiest to track
down. So it might be doable with BPF, but it does feel like the kernel
should do a better job of tracking out of the box and without
requiring too much plumbing and somewhat fragile kernel allocation API
tracking and probing from userspace.

Yeah, easy / default visibility argument does make sense to me.

So, a bit of addition here. If this is the thrust, the debugfs part seems
rather redundant, right? That's trivially obtainable with tracing / bpf and
in a more flexible and performant manner. Also, are we happy with recording
just single depth for persistent tracking?

Thanks.

-- 
tejun