Solved zfs very slow under "normal" load

alx82

alx82

I have a desktop system running 12-ALPHA3.

Under "normal" load, for example running the following command

Code: 
find Documents -type f -exec chmod 0644 {} \;

The system becomes quiet unresponsive until the command finishes. Documents contains 6G of latex/pdf files. This is on my zroot/usr/home dataset, system is installed using default parameters for zfs partitions offered by the installed.

Code: 
NAME            PROPERTY              VALUE                  SOURCE
zroot/usr/home  type                  filesystem             -
zroot/usr/home  creation              Tue Aug 14 12:19 2018  -
zroot/usr/home  used                  60.8G                  -
zroot/usr/home  available             345G                   -
zroot/usr/home  referenced            56.6G                  -
zroot/usr/home  compressratio         1.71x                  -


Is this is normal?
 
FreeBSD 12 (aka CURRENT) isn't supported on these forums. It's a developer snapshot which is considered unstable; there aren't even any guarantees that it will actually run.

See also this link: Topics about unsupported FreeBSD versions

As to slowness: I can well imagine that to be the case. Not only is CURRENT considered to be highly unstable; I'm pretty sure it's also jampacked with debug code to help find, reproduce and solve problems in the system.

You're much better off sticking with official releases, such as 11.2.
 
I know that CURRENT has a log of debug code enabled. I've recompiled the kernel with GENERIC-NODEBUG, and the system is quiet fast.

Thanks for the answer, but unfortunately I have to run CURRENT to get correct hardware support.
 
Ok I solved my problem. I had vfs.zfs.vdev.cache.size and vfs.zfs.arc_max set to low values, relaxing completely those two variables from loader.conf and my system flies!
 
The original values where rather low, I simply copied my loader.conf from an old machine (with 3GB of ram) to my new one :what:. On the old one I had tried to restrict the memory usage of zfs, but did not used much (now I'm running it with UFS).

Code: 
vfs.zfs.arc_max="200M"
vfs.zfs.vdev.cache.size="50M"

ATM those values are not set at all on my new machine which has16GB of RAM.
 
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