From: Wesley Darlington (wesley at domain yelsew.com)
Date: Fri 17 Aug 2001 - 10:39:12 IST
On Fri, Aug 17, 2001 at 10:14:05AM +0100, John P. Looney wrote:
> On Thu, Aug 16, 2001 at 06:51:39PM +0100, Ronan Cunniffe mentioned:
> > In other words, RAM disks *are* buffered in the conventional way...
> > but the pages are protected from being discarded, so all writes are
> > always to the buffer cache, and funny enough, they're never written out
> > to... um... where they're... um... actually stored....
>
> But...but...is there *any* compression done then, if they never leave the
> buffer cache ? Surely the compression is done between the disk & the VFS,
> not above the buffer cache layer...
Is there some crossing of lines here? AIUI, the original `ramdisk' used
memory very inefficiently, had writes stored in the buffer cache *and*
in its memory, didn't compress etc. Modern replacements like ramfs, cramfs,
tmpfs (?) all do things slightly differently. Is this (even vaguely)
correct?
Thanks,
Wesley.
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