/tmp on mfs
vince at unsane.co.uk
Tue Oct 20 19:13:01 UTC 2009
Christopher Hilton wrote:
> Reading the list yesterday I came across a little controversy about
> swap backed /tmp filesystems. I've been using this in my /etc/rc.conf
> tmpmfs="YES" # Set to YES to always create an mfs /tmp, NO
> to never
> tmpsize="1g" # Size of mfs /tmp if created
> tmpmfs_flags="-S -o async,noexec" # Extra mdmfs options for the
> mfs /tmp
> To mount /tmp on a swap backed filesystem. I've been assuming that
> data stored in the /tmp directory was held in RAM and then written to
> the swap space only when the system had a more pressing need for the
> RAM. I typically configure my systems with swap == 2 * RAM or more.
> And on the systems in question I have at least 1Gb of RAM. I was
> hoping to use this trick to enhance the performance of the postgresql
> database (temp_tablespace=/tmp/pgsql/....) Is my assumption about
> where the data in a temporary file is stored incorrect?
Thats certainly always been my interpretation of the manpage.
"Storage for this type of memory disk is allocated
buffer memory. Pages get pushed out to the swap when
the system is under memory pressure, otherwise
in the operating memory."
If thats not the case I'd be interested to know how it does work.
> -- Chris
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