Re: ZFS tunable parameters

[Greg Troxel <gdt%lexort.com@localhost>]

Brad Spencer <brad%anduin.eldar.org@localhost> writes:

> I left the ARC setting stock and performed my usual abuse build testing
> and I can say with certainly that it performed as one would expect.  No
> lock ups and while swapping was higher than with the adjustments
> mentioned in the patch, that would have been expected.  The system
> performed perfectly under pretty high memory pressure.

That is great news.  I expect that 11 will behave the same way, as I
think all the fixes have been pulled up (a while ago)

> I think I can say, at this point, that the fixes worked and worked very
> well.
>
> This is a very welcome change and brings the experience of using ZFS
> with NetBSD very close to what you could expect with Solaris.  There are
> likely more problems, in the form of missing support, still present with
> ZFS, expecially around failed devices, but in -current it works very
> well now with far fewer quirks.
>
> Thanks to everyone who made this a reality.

I think what really made the difference was yamt's fixes.  Before, our
code did not write back dirty pages that, I think, resulted from mmap,
and that's fixed, if I follow the diffs (but the underlying code is
complicated).

chuq identified a deadlock, where FreeBSD has two separate cleaner
threads in a way that matters for mmap-dirtied-pages.  I suspect that's
actually a problem but that it rarely matters now that we don't vastly
accumulated mmap-dirtied-pages.

I have not had a crash on my 11 box, and am going to update my desktop
from 10 to 11 soonish (async from whatever tags exist on netbsd-11 :-).
I hope that makes the same difference you see.  Currently, I perceive an
increasing over time since boot risk of crash, which fits with the bugs
yamt found.