Suggest changing dirhash defaults for FreeBSD 9.2.

[Ivan Voras]

On 29/08/2013 03:32, Dewayne Geraghty wrote:

> From the analysis perforned in 2009, and referenced earlier by Robert, this
> https://wiki.freebsd.org/DirhashDynamicMemory and other material at this site,
> indicates that the reclaimage interval is workload dependent and that 5 to 8 seconds seems, on average, to be adequate.

I'm having trouble understanding what the graphs are saying - you seem
to have almost consistently worse results with increasing dirhash memory
and/or reclaim age.

> Is the discussion, rather than (synthetic) workload
> performance, sufficient to warrant changing the default settings by a factor of 12? 

Yes, and also for an additional reason on top of what I've already said
in @fs and @hackers: it will be at least 10 years before someone
remembers to bumb this tunable again, so I consider a little overkill to
be ok.



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