DragonFly kernel List (threaded) for 2008-11
DragonFly BSD
DragonFly kernel List (threaded) for 2008-11
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Re: HEADS UP - HAMMER work


To: Dennis Melentyev <dennis.melentyev@xxxxxxxxx>
From: Michael Neumann <mneumann@xxxxxxxx>
Date: Sat, 15 Nov 2008 21:51:38 +0100

Dennis Melentyev schrieb:
2008/11/15 Michael Neumann <mneumann@ntecs.de>:
Dennis Melentyev schrieb:
...
Sysctl/some-other-tunable with some kind of mask would be great for
fine-tuning (and just useless for the 90% of users).

like:
sysctl.hammer.dirhash.hashmask.prefix=1 (Starting at first filename
byte, 3 bytes fixed length)
sysctl.hammer.dirhash.hashmask.suffix=-1 (Starting last byte, 2 bytes
length)
Hm, but the hash is stored on-disk within each b-tree node, so changing the
hash-function becomes pretty dangerous!

That could be done via an option upon PFS creation, changed with "hammer" utility parameter, whatever else way. As I wrote: "sysctl/some-other-tunable".

Ah okay. A per-PFS setting would make sense to me.


Anyway, for me, it is fine tuning issue. Quite rare and very special
one. I hardly see any need in such thing for 99% of installations, but
there sure are cases when it is a huge plus.

That's why I'd prefer to just have one good heuristic which is in any way better than what UFS provides.


Regards,

Michael



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