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

Reindl Harald h.reindl at thelounge.net
Fri Jun 1 20:54:58 UTC 2012

Am 01.06.2012 22:44, schrieb Gregory Maxwell:
> On Fri, Jun 1, 2012 at 12:32 PM, Reindl Harald <h.reindl at thelounge.net> wrote:
>> if they are on disk under /tmp they are cached only
>> as long page-cache or active RAM is not needed for
>> the workload and the memory can be released instead
>> WRITE it do disk with swapping
> This is how tmpfs works too, except without tmpfs some write activity
> is required because the metadata updates (and data for sufficiently
> long lived tmp files) will be written to disk.   So what the normal
> buffer cache does for reading tmpfs lets it also do for writing.

no - there is a difference

page-cache is simply freed for application use at memory allocation
if you run out of memory beause a large tmpfs it forces the system
to use SWAP

this happens usually while a application is allocating a large
amount of memory and your system is under pressure, what happens
with /tmp on tmpfs causes this swap in such moments is that your
whole system will be really slow

if your workload at the same time needs access to applications
which are swapped out you can go to get some coffee, there is
no system on this world which will not get crippled performance
due high swap load

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