Re: [RFC] Documentation/filesystems/tmpfs

From: Padraig Brady (padraig@antefacto.com)
Date: Wed Nov 28 2001 - 12:30:21 EST


Christoph Rohland wrote:

> Hi,
>
> Apparently there is a lack of information about tmpfs out there.

I aggree, and ramfs et al.

> So I would like to reduce the Configure.help entry and instead
> introduce a file Documentation/filesystems/tmpfs with more details.
>
> My proposal is appended. Feedback about content and english language
> is highly appreciated.
>
> Greetings
> Christoph
>
> ------------------------------------------------------------------------
>
> Tmpfs is a file system which keeps all files in virtual memory.
>
> Everything is temporary in the sense that no files will be created on
> your hard drive. If you reboot, everything in tmpfs will be lost.
>
> In contrast to RAM disks, which get allocated a fixed amount of
> physical RAM, tmpfs grows and shrinks to accommodate the files it
> contains and is able to swap unneeded pages out to swap space.

That isn't the case now since ramdisks were

integrated with the buffer cache:

$ dd if=/dev/zero of=/tmp/use_mem bs=1024 count=20000
$ cat /proc/meminfo
         total: used: free: shared: buffers: cached:
Mem: 129966080 122720256 7245824 49152 65863680 28745728
Swap: 0 0 0
MemTotal: 126920 kB
MemFree: 7076 kB
MemShared: 48 kB
Buffers: 64320 kB
Cached: 28072 kB
SwapCached: 0 kB
Active: 10308 kB
Inact_dirty: 80196 kB
Inact_clean: 1936 kB
Inact_target: 26200 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 126920 kB
LowFree: 7076 kB
SwapTotal: 0 kB
SwapFree: 0 kB

$ rm /tmp/use_mem
$ cat /proc/meminfo
         total: used: free: shared: buffers: cached:
Mem: 129966080 101957632 28008448 49152 65863680 8290304
Swap: 0 0 0
MemTotal: 126920 kB
MemFree: 27352 kB
MemShared: 48 kB
Buffers: 64320 kB
Cached: 8096 kB
SwapCached: 0 kB
Active: 10352 kB
Inact_dirty: 60196 kB
Inact_clean: 1916 kB
Inact_target: 26200 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 126920 kB
LowFree: 27352 kB
SwapTotal: 0 kB
SwapFree: 0 kB

Padraig.

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This archive was generated by hypermail 2b29 : Fri Nov 30 2001 - 21:00:31 EST