From: Jamie Lokier [mailto:jamie@shareable.org]
Subject: Re: [PATCH V2 0/7] Cleancache (was Transcendent Memory):
overview

Dan Magenheimer wrote:

quoted

Most important, cleancache is "ephemeral".  Pages which are copied

into

quoted

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.

quoted

Thus, as its name implies, cleancache is not suitable for dirty

pages.  The

quoted

pseudo-RAM has complete discretion over what pages to preserve and

what

quoted

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

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