On 15/06/21 07:25, Leon Romanovsky wrote:
Sorry for my naive questions, but how does telemetry get statistics for hypervisors? Why is KVM different from hypervisors or NIC's statistics or any other high speed devices (RDMA) that generate tons of data?
Right now, the only way is debugfs but it's slow, and it's disabled when using lockdown mode; this series is a way to fix this.
I sense that there is another question in there; are you wondering if another mechanism should be used, for example netlink? The main issue there is how to identify a VM, since KVM file descriptors don't have a name. Using a pid works (sort of) for debugfs, but pids are not appropriate for a stable API. Using a file descriptor as in this series requires collaboration from the userspace program; howver, once the file descriptor has been transmitted via SCM_RIGHTS, telemetry can read it forever without further IPC, and there is proper privilege separation.
Paolo
