From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: a ton of kernel issues Date: Tue, 13 Dec 2011 17:38:56 -0400 Message-ID: <20111213213856.GA29005@andromeda.dapyr.net> References: <4EE675A8.3030609@niemail.de> <4EE71663.5040308@gmail.com> <4EE72A94.6040904@gmail.com> <20111213141835.GA32247@andromeda.dapyr.net> <4EE7BF4F.7030700@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <4EE7BF4F.7030700@gmail.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: George Shuklin Cc: xen-devel@lists.xensource.com, sandr8@gmail.com List-Id: xen-devel@lists.xenproject.org On Wed, Dec 14, 2011 at 01:10:39AM +0400, George Shuklin wrote: > On 13.12.2011 18:18, Konrad Rzeszutek Wilk wrote: > > >>>what glitches should one expect with 3.0+, and having the choice, > >>>would it be better to go with 3.1 or even 3.2? > >>> > >>Right now I know about two of them: > >>When you set up memory for virtual machine using xenballon, value in > >>dom0 differ from value in domU. The issue is that -xen kernels 'hide' > >>some memory in 'used' memory, and pv-ops just reducing TotalMem to value > >>without that memory. Practically that means if you set up memory for > >>domain to 2GiB client will saw only 1.95GiB and so on. > >> > >>The second issue is lack of support of 'pre-inflated balloon', means you > >>can not set up memory-static-max to 2GiB, target to 1GiB and do 'memory > >>grow' from 1 G to 2 G latter without VM reboot. -xen kernels allow this > >>(up to memory-static-max limit). > >Is all of this with 'xm' or with 'xl' tools? What happens when you 'grow' > >the memory from 1G to 2G? Are you using the hotplug memory balloon or > >the older one? > This is xcp (with shutdowned squeezed, it not a problem), so we using > direct calls to xc (domain_set_maxkb), but I can repeat this with xl > (which one and only one available in XCP), with same results. If I > create VM with static-max 2GiB, dynamic-max 1GiB, boot it, then: > > 1) with PV_ops I can go lower than 1GiB, but never any higher than 1GiB I just tried this, and had these two options in my guest config: maxmem=2048 mem=1024 booted up the guest and from dom0 did "xm mem-set latest 2048" and it expanded to 2G. Did "xm mem-set latest 10248" and it went down. Is this how you are doing it as well? (I have to confess I don't know much about XCP so don't know if those 'static-max, dynamic-max' are the same thing). Is this PV bootup? Or HVM? > 2) with -xen kernels I can go upper to 2GiB. > > If I compile kernel with xenballoon hotplug option enabled, after some > (very small) memory growth (within preallocated memory?) after future > attempts I getting this message: > > [1935380.223401] System RAM resource 18000000 - 27ffffff cannot be added > [1935380.223414] xen_balloon: reserve_additional_memory: add_memory() > failed: -17 Hm, that looks like a bug. But the old style balloon code does work. Not sure why with a default .config you are hitting these issues. > > (tested with vanilla 3.0, 3.1 and some RCs of 3.2) > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel