Re: ZFS arc_reclaim_needed: better cooperation with pagedaemon

on 23/08/2010 10:28 Artem Belevich said the following:
If we could also deal with zone fragmentation issue you've written in
another thread, that should bring ZFS even closer to being usable
without shaman-style (the one with lots of muttering, swearing and
dancing around) tuning.

Actually, it may be worth trying your test with re-enabled UMA
allocator for ARC. Now that pagedaemon will be running, it would also
invoke UMA's low memory handlers and those should be able to give some
memory back to the system.

I tried, but still no go (for my taste).
The fragmentation is too high and very significant portion of memory is
effectively lost to it.
E.g. ARC may think that it uses only 1GB but another 1GB is used by free items
in ZFS zones (of 4GB total).

--
Andriy Gapon
_______________________________________________
freebsd-hackers@xxxxxxxxxxx mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@xxxxxxxxxxx"

Relevant Pages

  • Re: ZFS vs OSX Time Machine
    ... It would be useful to provide ZFS ARC sysctl data from the FreeBSD ... There's some speculation that memory fragmentation has something to do ...
    (freebsd-stable)
  • Re: zfs arc and amount of wired memory
    ... I think that examination of vmstat -m and vmstat -z outputs may provide some ... clues as to what got all that memory wired. ... This is old 7.3 with ZFS v13, that's why I did not reported it. ... ARC Size: ...
    (freebsd-stable)
  • Re: vm.kmem_size settings doesnt affect loader?
    ... ARC tuning is what's necessary to induce ZFS memory constraints. ... grows to such a size that kmem exhaustion happens. ...
    (freebsd-stable)
  • Re: Fileserver panic - FreeBSD 8.1-stable and zfs
    ... This is a well-known thing with ZFS on FreeBSD. ... There are certain conditions where ZFS will take up more memory than ... E.g. if you limit the ARC to 2GB and use top, ... Keep reading for tuning advice. ...
    (freebsd-stable)
  • Re: vm.kmem_size settings doesnt affect loader?
    ... If your machine has some small amount of memory, ... I know that i386 is highly unrecommended for ZFS, but it's just a home box for testing and learning purposes - I just want to know what I'm doing and what should I expect when I decide to put ZFS on server machines:) Currently, from posts on freebsd-fs, I conclude that even with a gigs of kmem and using AMD64, we still can experience panic from kmem_malloc. ... Of course I've followed tuning guide carefully. ...
    (freebsd-stable)