On Tue, Jun 15, 2021 at 01:03:34PM +0200, Paolo Bonzini wrote: > On 15/06/21 09:53, 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? > > > > So the answer to the question "why KVM is different" is that it doesn't > > have any stable identification except file descriptor. While hypervisors > > have stable names, NICs and RDMA devices have interface indexes etc. > > Did I get it right? > > Right. > > > And this was second part of my question, the first part was my attempt to > > get on answer why current statistics like process info (/proc/xxx/*), NICs > > (netlink) and RDMA (sysfs) are not using binary format. > > NICs are using binary format (partly in struct ethtool_stats, partly in an > array of u64). For KVM we decided to put the schema and the stats in the > same file (though you can use pread to get only the stats) to have a single > interface and avoid ioctls, unlike having both ETH_GSTRINGS and ETH_GSTATS. > > I wouldn't say processes are using any specific format. There's a mix of > "one value per file" (e.g. cpuset), human-readable tabular format (e.g. > limits, sched), human- and machine-readable tabular format (e.g. status), > and files that are ASCII but not human-readable (e.g. stat). I see, your explanation to Enrico cleared the mud. Thanks > > Paolo >
