Re: pgdaemon high CPU consumption

[mlelstv%serpens.de@localhost (Michael van Elst)]

mp%petermann-it.de@localhost (Matthias Petermann) writes:

>since some time I noticed that on several of my systems with=20
>NetBSD/amd64 9.99.97/98 after longer usage the kernel process pgdaemon=20
>completely claims a CPU core for itself, i.e. constantly consumes 100%.
>The affected systems do not have a shortage of RAM and the problem does=20
>not disappear even if all workloads are stopped, and thus no RAM is=20
>actually used by application processes.

There is a shortage, either free RAM pages or kernel address space.

The page daemon gets triggered, but if it cannot resolve the situation
it will just spin until it succeeds.


>I noticed this especially in connection with accesses to the ZFS set up=20
>on the respective machines - for example after checkout from the local=20
>CVS relic hosted on ZFS.

Resource exhaustion could be caused by ZFS, but also something else.

If you can still operate the system, a common workaround is to
reduce kern.maxvnodes with sysctl (and bump it up later).

If the system is not responding but you can enter DDB, setting
the kernel variable desiredvnodes does the same.