From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: xen: memory initialization/balloon fixes (#3) Date: Thu, 22 Sep 2011 13:32:26 +0100 Message-ID: <4E7B2ADA.7000605@citrix.com> References: <1316089768-22461-1-git-send-email-david.vrabel@citrix.com> <63997331-e53b-48e5-bf7c-87141aae49d6@default> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <63997331-e53b-48e5-bf7c-87141aae49d6@default> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dan Magenheimer Cc: "xen-devel@lists.xensource.com" , Wilk , Konrad List-Id: xen-devel@lists.xenproject.org On 20/09/11 17:57, Dan Magenheimer wrote: > > Thanks for your patches! I am looking at a memory capacity/ballooning > weirdness that I hoped your patchset might fix, but so far it has not. > I'm wondering if there was an earlier fix that you are building upon > and that I am missing. > > My problem occurs in a PV domU with an upstream-variant kernel based > on 3.0.5. The problem is that the total amount of memory as seen > from inside the guest is always substantially less than the amount > of memory seen from outside the guest. The difference seems to > be fixed within a given boot, but assigning a different vm.cfg mem= > changes the amount. (For example, the difference D is about 18MB on > a mem=128 boot and about 36MB on a mem=1024 boot.) I don't see the problem? The MemTotal value /proc/meminfo doesn't include some pages reserved by the kernel which is why it's less than the maximum reservation of the domain. > Part B of the problem (and the one most important to me) is that > setting /sys/devices/system/xen_memory/xen_memory0/target_kb > to X results in a MemTotal inside the domU (as observed by > "head -1 /proc/meminfo") of X-D. This can be particularly painful > when X is aggressively small as X-D may result in OOMs. > To use kernel function/variable names (and I observed this with > some debugging code), when balloon_set_new_target(X) is called > totalram_pages gets driven to X-D. Again, this looks like the correct behavior to me. David