Also seeing 2 x quad-core system slower that 2 x dual core

Alexey Popov lol at
Thu Nov 29 23:17:05 PST 2007


Pete French wrote:
>> Have you checked that your dir hash isn't suffering due to lack of memory
>> this can have a marked impact on seemingly trivial things like this as
>> could silly things like the RAID card being installed in a different slot.
> RAID card is onboard on these things - how would I check the dir hash ? The
> slower server has 16 gig of RAM, the faster one has 4 gig. Both were
> installed the same way in the same order, so should have the same disc layout
> more or less.
dirhash is a cache of directories that store many files. FreeBSD has 
unreasonably small default for the maximum size of this cache.

See sysctl -a | grep dirhash and tune up vfs.ufs.dirhash_maxmem if 
vfs.ufs.dirhash_mem is near to the limit.

Also could you please provide `top` and `systat -vm 1` output on dual- 
and quad-core systems during your tests?

With best regards,
Alexey Popov

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