From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx162.postini.com [74.125.245.162]) by kanga.kvack.org (Postfix) with SMTP id E871B6B0005 for ; Wed, 6 Feb 2013 14:09:27 -0500 (EST) Received: by mail-pa0-f50.google.com with SMTP id fa11so1007730pad.9 for ; Wed, 06 Feb 2013 11:09:27 -0800 (PST) Date: Wed, 6 Feb 2013 11:09:24 -0800 From: Greg KH Subject: Re: [PATCH] staging/zcache: Fix/improve zcache writeback code, tie to a config option Message-ID: <20130206190924.GB32275@kroah.com> References: <1360175261-13287-1-git-send-email-dan.magenheimer@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1360175261-13287-1-git-send-email-dan.magenheimer@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dan Magenheimer Cc: devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ngupta@vflare.org, konrad.wilk@oracle.com, sjenning@linux.vnet.ibm.com, minchan@kernel.org On Wed, Feb 06, 2013 at 10:27:41AM -0800, Dan Magenheimer wrote: > It was observed by Andrea Arcangeli in 2011 that zcache can get "full" > and there must be some way for compressed swap pages to be (uncompressed > and then) sent through to the backing swap disk. A prototype of this > functionality, called "unuse", was added in 2012 as part of a major update > to zcache (aka "zcache2"), but was left unfinished due to the unfortunate > temporary fork of zcache. > > This earlier version of the code had an unresolved memory leak > and was anyway dependent on not-yet-upstream frontswap and mm changes. > The code was meanwhile adapted by Seth Jennings for similar > functionality in zswap (which he calls "flush"). Seth also made some > clever simplifications which are herein ported back to zcache. As a > result of those simplifications, the frontswap changes are no longer > necessary, but a slightly different (and simpler) set of mm changes are > still required [1]. The memory leak is also fixed. > > Due to feedback from akpm in a zswap thread, this functionality in zcache > has now been renamed from "unuse" to "writeback". > > Although this zcache writeback code now works, there are open questions > as how best to handle the policy that drives it. As a result, this > patch also ties writeback to a new config option. And, since the > code still depends on not-yet-upstreamed mm patches, to avoid build > problems, the config option added by this patch temporarily depends > on "BROKEN"; this config dependency can be removed in trees that > contain the necessary mm patches. I'll wait for those options to be in Linus's tree before accepting a patch like this, sorry. greg k-h -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org