ZFS dedup write pathway - possible inefficiency or..?

Stilez Stilezy stilezy at gmail.com
Mon Apr 2 18:30:36 UTC 2018

Thanks on that tip, Andriy,

I don't have the knowledge to tell if that's the first of the 2 issues I'm
seeing.  It could be. What exactly is that bug describing and what
behaviour would it create?

Assuming it's the same -

1) Are there any known workarounds or sysctls that help to reduce the issue?

2) Are there any easy diagnostic tests I can easily do, to confirm if this
is the same behaviour as that bug?  Nobody else uses the test system, so I
can change any sysctls to sane or extreme values for testing, or create
large txg's and spread out reads and writes to see what's happening and
what coincides with what.

Thanks again

On 2 April 2018 at 18:47, Andriy Gapon <avg at freebsd.org> wrote:

> On 02/04/2018 16:36, Stilez Stilezy wrote:
> > The first issue is specific to the
> > dedup write pathway.   I've tested locally to a point where it seems it's
> > not due to inadequate hardware and it's very consistent and specific,
> even
> > on idle conditions/minimal load.  I'm wondering whether there's a code
> > bottleneck specifically affecting just the dedup write pathway.
> I think that this might be https://www.illumos.org/issues/8353
> --
> Andriy Gapon

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