Re: [PATCH] kvm: no need to check return value of debugfs_create functions

[Paolo Bonzini]

On 22/01/19 21:48, Greg Kroah-Hartman wrote:
>> This also brings the question: shall we move these counters out of debugfs into something else?
> If you have code that relies on debugfs, yes, you need to move that out
> of debugfs because more and more systems are trying to disable it due to
> the obvious problems with it (i.e. leaking tons of debugging
> information).
> 
> debugfs is for DEBUG information, not for "statistics about how my VM is
> working".  That sounds like something you need to rely on, so debugfs is
> not the place for it.

Yes, we know that and tracepoints are already one replacement.  However,
they are slower that just a lock-free "vcpu->stats.foo_happened++".
Another idea that Steven Rostedt and I discussed a while ago is some
kind of "statfs" which would already provide some code, similar to the
one that KVM uses to accumulate statistics from multiple VMs or multiple
VCPUs into a single counter.

Paolo