From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Magenheimer Date: Wed, 02 Jun 2010 15:36:00 -0000 Subject: [Ocfs2-devel] [PATCH V2 0/7] Cleancache (was Transcendent Memory): overview In-Reply-To: <20100602130014.GB7238@shareable.org> References: <20100528173510.GA12166@ca-server1.us.oracle.com 20100602130014.GB7238@shareable.org> Message-ID: <312cfff6-7ee7-4a6e-a3fd-fc9b6893f0b1@default> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jamie Lokier Cc: chris.mason@oracle.com, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, adilger@sun.com, tytso@mit.edu, mfasheh@suse.com, joel.becker@oracle.com, matthew@wil.cx, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, ocfs2-devel@oss.oracle.com, linux-mm@kvack.org, ngupta@vflare.org, jeremy@goop.org, JBeulich@novell.com, kurt.hackel@oracle.com, npiggin@suse.de, dave.mccracken@oracle.com, riel@redhat.com, avi@redhat.com, konrad.wilk@oracle.com > 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