Increasing ufs.dirhash_maxmem by default
Ivan Voras
ivoras at freebsd.org
Sat Oct 9 19:52:13 UTC 2010
hi,
Several people have worked on dirhash in the past so I'm posting here
instead of individually pinging them.
The default dirhash_maxmem is currently set as 2 MB, which while may be
sufficient some time ago it certainly isn't now. I've had to increase it
on practically all non-trivial servers and even high-end desktops, and
there are occasional reports on the lists that suggest it's a fairly
common thing.
What I'd like to do is either:
1) Simply increase the default to e.g. 32 MB (trivial change) or
2) Make it a function of hibufspace (e.g. 1/32th of it, capped at 64 MB)
which is itself autotuned. This would happen in ufsdirhash_init().
The current incarnation of dirhash has a vm_lowmem handler so it doesn't
look like it could starve a system if overtuned.
Ideas? Objections?
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