Suggest changing dirhash defaults for FreeBSD 9.2.

[Robert Burmeister]

On 8/27/2013 9:40 AM, Sergey Kandaurov wrote:
> On 27 August 2013 16:41, Robert Burmeister
> <Robert.Burmeister at utoledo.edu>  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.
>
[Spock Eyebrow of Thought]

I'm running FreeBSD i386 9.2, that allows a max of 4 Gigs of RAM.

I think the algorithm is still overly conservative for 32 bit systems,
which are more likely to be using UFS.

As 64 bit platforms tend to have more RAM and use ZFS,
is the same tuning algorithm appropriate for both?