Google Opens Patches For "METRICFS" That They Have Used Since 2012 For Telemetry Data

The METRICFS file-system has been in use internally at Google since 2012 for exporting system statistics to their telemetry systems with around 200 statistics being exported per machine. They are now posting the METRICFS patches as open-source for review and possible upstreaming.

A "request for comments" on METRICFS was sent out today on the Linux kernel mailing list. Their motives for now finally publishing these patches is as a result of the recent Statsfs proposal by a Red Hat engineer for a RAM-based file-system for exposing kernel statistics to user-space. METRICFS has a similar aim to Statsfs.

The posted METRICFS code has been cleaned up and modernized compared to Google's internal production version. These statistics reside under DebugFS and each metric being exposed in its own directory and contained within there are files for the annotations, fields, values, and version.

"Google has found a lot of value in having a generic interface for adding these kinds of statistics with reasonably low overhead (reading them is O(number of statistics), not number of objects in each statistic)," commented Google's Jonathan Adams.

More details on the METRICFS implementation via this mailing list thread.