Am 01.06.2012 22:44, schrieb Gregory Maxwell: > On Fri, Jun 1, 2012 at 12:32 PM, Reindl Harald <h.reindl@xxxxxxxxxxxxx> 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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