[Ocfs2-devel] [PATCH V2 0/7] Cleancache (was Transcendent Memory): overview

[Dan Magenheimer]

> From: Jamie Lokier [mailto:jamie at shareable.org]
> Subject: Re: [PATCH V2 0/7] Cleancache (was Transcendent Memory):
> overview
> 
> Dan Magenheimer wrote:
> > Most important, cleancache is "ephemeral".  Pages which are copied
> into
> > cleancache have an indefinite lifetime which is completely unknowable
> > by the kernel and so may or may not still be in cleancache at any
> later time.
> > Thus, as its name implies, cleancache is not suitable for dirty
> pages.  The
> > pseudo-RAM has complete discretion over what pages to preserve and
> what
> > pages to discard and when.
> 
> Fwiw, the feature sounds useful to userspace too, for those things
> with memory hungry caches like web browsers.  Any plans to make it
> available to userspace?

No plans yet, though we agree it sounds useful, at least for
apps that bypass the page cache (e.g. O_DIRECT).  If you have
time and interest to investigate this further, I'd be happy
to help.  Send email offlist.

Thanks,
Dan