[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] can not use all available memory
On Fri, Nov 23, 2012 at 12:47:07PM +0000, Ian Campbell wrote: > On Fri, 2012-11-23 at 12:41 +0000, Pasi Kärkkäinen wrote: > > On Fri, Nov 23, 2012 at 12:33:59PM +0000, Ian Campbell wrote: > > > On Fri, 2012-11-23 at 12:28 +0000, Pasi Kärkkäinen wrote: > > > > On Fri, Nov 23, 2012 at 12:21:32PM +0000, Ian Campbell wrote: > > > > > This question belongs on xen-users. > > > > > > > > > > On Fri, 2012-11-23 at 11:35 +0000, Alexander Bienzeisler wrote: > > > > > > Hello, > > > > > > > > > > > > i just tried to add a domU with 16 gigs of ram (maxmem = 16384, > > > > > > memory = > > > > > > 16384) with free_memory : 28969 but got an error: > > > > > > > > > > > > libxl: error: libxl.c:3433:libxl_set_memory_target: new target 0 > > > > > > for > > > > > > dom0 is below the minimum threshold > > > > > > > > > > The clue is in this message -- you cannot safely balloon down a guest > > > > > (including dom0) to an arbitrarily small value relative to its initial > > > > > size. The kernel will have certain fixed datastructures etc which are > > > > > sized according to the maximum amount of RAM at start of day. > > > > > > > > > > If you were to balloon down too low then you would run out of RAM and > > > > > the OOM killer would step in and start killing stuff, so xl includes a > > > > > safety catch which prevents this. > > > > > > > > > > If you have a huge host and want a small dom0 use the dom0_mem option > > > > > and disable xl's autoballoon option or whatever the equivalent xend > > > > > option is. > > > > > > > > > > > > > I think he was already using dom0_mem. He had 28969 free in Xen as > > > > reported by "xl info". > > > > > > Then he's missed disabling autoballoon. > > > > > > > As can be seen from the other email in this thread, > > he's using dom0_mem=2048M, and he has 28GB of free memory in Xen. > > > > Why is xl trying to balloon down dom0 (and failing) for no reason? > > Because autoballoon is enabled. > Yep, autoballoon=0 fixed the problem. > This has been discussed at length on the list before, please check the > archives. > I tried googling quickly but I didn't find anything relevant.. To me this behaviour still seems wrong. What's the point of autoballoon=1 trying to balloon down dom0 if the hypervisor already has enough free memory for the VM ? In this case: - dom0_mem=2G - new VM to launch with size 16 GB. - Xen has 28 GB of free memory. So clearly there's no need to try to balloon down dom0.. not-yet-implemented check/feature in xl, or a bug? Thanks, -- Pasi _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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