On Mon, 19 Jan 2026 10:54:13 +0100 Jesper Dangaard Brouer wrote:

On 19/01/2026 09.49, Leon Hwang wrote:

quoted

quoted

My input here is the least valuable (since one may expect the person
who added the code uses it) - but FWIW yes, we do use the PP stats to
monitor PP lifecycle issues at Meta. That said - we only monitor for
accumulation of leaked memory from orphaned pages, as the whole reason
for adding this code was that in practice the page may be sitting in
a socket rx queue (or defer free queue etc.) IOW a PP which is not
getting destroyed for a long time is not necessarily a kernel issue.
 

What monitoring tool did production people add metrics to?

People at CF recommend that I/we add this to prometheus/node_exporter.
Perhaps somebody else already added this to some other FOSS tool?

https://github.com/prometheus/node_exporter

We added it to this:

  https://github.com/facebookincubator/dynolog

But AFAICT it's missing from the open source version(?!)

Luckily ynltool now exists so one can just plug it into any monitoring
system that can hoover up JSON:

  ynltool -j page-pool stats