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

Brian Wheeler bdwheele at indiana.edu
Wed Jun 20 18:06:07 UTC 2012

On 06/20/2012 01:55 PM, Chris Adams wrote:
> Once upon a time, Brian Wheeler <bdwheele at indiana.edu> said:
>> So, how does this scenario work?
>> * The machine has 4G of RAM,
>> * > 50% RAM is being used by actual software (firefox, eclipse, mail
>> client, etc), so the other < 50% is pagecache
>> * The machine has 4G of swap, none of which is active.
>> So then a user drops a 8.5G DVD image into /tmp.
>> On a traditional /tmp-on-disk if it filled up then you'd get an ENOSPC
>> and user things can't write to disk, but the OS will be fine since 5% is
>> reserved for root.
>> With tmpfs the pagecache will fill up and start to overflow to
>> swap...until swap fills up. What happens then?
> 2G gets written and then -ENOSPC.  2G gets pushed to swap.
> The default for tmpfs mounts is an fs that is sized to RAM/2.

So the default is that I can use 2G in /tmp regardless of how much swap 
is present if the system memory size is 4G?  So the only way to get more 
/tmp is to either mess with the max% or buy more ram?

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