On 8/27/2013 9:40 AM, Sergey Kandaurov wrote:
On 27 August 2013 16:41, Robert Burmeister
<[email protected]> wrote:
I have been experimenting with dirhash settings, and have scoured the internet
for other peoples' experience with it.
(I found the performance improvement in compiling has forestalled the need to
add an SSD drive. ;-)
I believe that increasing the following values by 10 would benefit most FreeBSD
users without disadvantage.
vfs.ufs.dirhash_maxmem: 2097152 to 20971520
vfs.ufs.dirhash_reclaimage: 5 to 50 or 60
vfs.ufs.dirhash_maxmem is further autotuned based on available physical memory.
See r214359 for details.
Sorry, the documentation has not been updated since 2008.
https://wiki.freebsd.org/DirhashDynamicMemory
What about bumping up vfs.ufs.dirhash_reclaimage
all hashes older than 5 seconds (tunable via a sysctl,
vfs.ufs.dirhash_reclaimage) will always be deleted when a vm_lowmem event
occurs, and if that doesn't free up at least 10% of the memory currently being
used by dirhash, more hashes will be destroyed from the head of the TAILQ
until we do free up at least 10% of the memory initially used.
As the memory scavenger will keep nibbling until at least 10% of the cache is
free,
eradicating all entries older than 5 seconds for the first chop seems overly
aggressive.
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