Re: [HEADS-UP] Rawhide: /tmp is now on tmpfs

[Bob Proulx]

Pádraig Brady wrote:
> Thinking a bit more about this, as I see it:
> 
>   /tmp =     stateless
>   /var/tmp = stateful

Yes.  Because /tmp is typically cleared on a reboot.  But reboots are
either scheduled regularly *or* never scheduled and can be quite few
and far between.  But that is a different topic...

> What is actually used to back those paths is system specific
> and inconsequential to `sort`. `sort` logically just needs stateless
> storage, as after sort exits, its tmp files are no longer useful.
> If `sort` could restart operations then that would be a different story.
> 
> So `sort` should stick to /tmp I think, and not worry
> about system implementation details.

+1

I think sort should stick to /tmp since that is the behavior most
people would expect.  There is always TMPDIR for customization.  For
/tmp tmpfs systems they will simply have to deal with it.  Dealing
with it probably means setting the size appropriately and making swap
space available.  But usage strategies vary.  Desktops, basic servers,
servers running particular tasks, will all have different needs.

> Another pertinent piece of info is that Debian
> have reverted the default setting of tmpfs backed /tmp:
> http://packages.debian.org/changelogs/pool/main/s/sysvinit/current/changelog#version2.88dsf-26

And personally I am happy.  The rolled out implementation of /tmp as
50% of physical ram was way too small on small memory machines when
there were gigs and gigs of disk available.  (A 512M ram machine with
a 500G disk would have a 256M /tmp.)

For a while then it was a percentage of virtual memory.  But some
people haven't been including any swap space and relying upon Linux
memory overcommit behavior and therefore again had a way too small
/tmp.  They would need to add swap space and reconfigure in order to
have a large enough /tmp.

In some ways it is a tradeoff between banking disk space for use as
/tmp as filesystem or banking disk space as swap for use as backing
for tmpfs.

I always turn off Linux memory overcommit and then configure enough
swap space to ensure sufficient virtual memory.  So for me a
reasonable /tmp isn't that much of a hardship.  Since I already had a
significant amount of swap space configured.  And use lvm so that I
can add more easily.  But even I need to add more when using a
reasonable sized /tmp tmpfs.  And by reasonable sized I mean large
enough to use for temporary space for video editing.  :-)

Bob