about the tmpmfs="YES" in rc.conf

[Giorgos Keramidas]

On 2004-11-11 16:36, LEI CHEN <adam.chen at tpg.com.au> wrote:
>On Thu, 2004-11-11 at 16:11, Giorgos Keramidas wrote:
>>On 2004-11-11 04:36, LEI CHEN <adam.chen at tpg.com.au> wrote:
>>>On Thu, 2004-11-11 at 03:44, Giorgos Keramidas wrote:
>>>> If you're using the -pipe option of gcc, it shouldn't make such a
>>>> great difference where /tmp is.  I suspect it will make a HUGE
>>>> difference where your /usr/obj tree is stored though.
>>>
>>> yes, I've read this in the handbook, /usr/obj shadows /usr/src
>>> directories.  But how can I put it into memory?
>>
>> Using mdmfs(8).  The mdmfs(8) utility is what does all the work
>> behind the tmpmfs="YES" option in rc.conf.
>
> I've found this url
> http://bsdvault.net/sections.php?op=viewarticle&artid=53
> very helpful.
>
> But I got only 256Mb of memory, so I can't mount 300Mb mfs into RAM.

Hmm, then it's probably not a very good idea to mount /usr/obj as a
memory disk.  Using swap backed (instead of malloc backed) md file
systems is something I haven't tested, but my intuition says it's not
going to be much faster than using a real disk partition.  It's more
likely to be slower, IMHO.

> And therefore I can only mount 128Mb or so. Well in this case, would
> there be a memory overflow during make world? And what to do if this
> is the case?

A filesystem overflow (and a broken buildworld because of the
inability to write some object files), yes.  A memory overflow,
no, not really.