"J. Hannken-Illjes" <hann...@mailbox.org> writes: >> On 1. Jul 2022, at 07:55, Matthias Petermann <m...@petermann-it.de> wrote: >> >> Good day, >> >> since some time I noticed that on several of my systems with NetBSD/amd64 >> 9.99.97/98 after longer usage the kernel process pgdaemon 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 not >> disappear even if all workloads are stopped, and thus no RAM is actually >> used by application processes. >> >> I noticed this especially in connection with accesses to the ZFS set up on >> the respective machines - for example after checkout from the local CVS >> relic hosted on ZFS. >> >> Is there already a known problem or what information would have to be >> collected to get to the bottom of this? >> >> I currently have such a case online, so I would be happy to pull diagnostic >> information this evening/afternoon. At the moment all info I have is from >> top. >> >> Normal view: >> >> ``` >> PID USERNAME PRI NICE SIZE RES STATE TIME WCPU CPU COMMAND >> 0 root 126 0 0K 34M CPU/0 102:45 100% 100% [system] >> ``` >> >> Thread view: >> >> >> ``` >> PID LID USERNAME PRI STATE TIME WCPU CPU NAME COMMAND >> 0 173 root 126 CPU/1 96:57 98.93% 98.93% pgdaemon [system] >> ``` > > Looks a lot like kern/55707: ZFS seems to trigger a lot of xcalls > > Last action proposed was to back out the patch ... > > -- > J. Hannken-Illjes - hann...@mailbox.org
Probably only a slightly related data point, but Ya, if you have a system / VM / Xen PV that does not have a whole lot of RAM and if you don't back out that patch your system will become unusable in a very short order if you do much at all with ZFS (tested with a recent -current building pkgsrc packages on a Xen PVHVM). The patch does fix a real bug, as NetBSD doesn't have the define that it uses, but the effect of running that code will be needed if you use ZFS at all on a "low" RAM system. I personally suspect that the ZFS ARC or some pool is allowed to consume nearly all available "something" (pools, RAM, etc..) without limit but have no specific proof (or there is a leak somewhere). I mostly run 9.x ZFS right now (which may have other problems), and have been setting maxvnodes way down for some time. If I don't do that the Xen PV will hang itself up after a couple of 'build.sh release' runs when the source and build artifacts are on ZFS filesets. -- Brad Spencer - b...@anduin.eldar.org - KC8VKS - http://anduin.eldar.org