Re: [Xen-users] CentOS 6.2 & xl mem-set

[Ivan Fitenko <digitalhunger@xxxxxxxxx>]

Balooning feature seems to be broken in CentOS/RHEL 6 stock kernels. You will 
need to patch your guest kernel to make it work again.
Here is the patch against 2.6.32-220.el6 (backported from 3.1.6):

diff -Naru a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
--- a/arch/x86/xen/setup.c      2011-11-08 23:06:47.000000000 +0200
+++ b/arch/x86/xen/setup.c      2012-01-04 16:30:19.468207563 +0200
@@ -146,9 +146,20 @@
        domid_t domid = DOMID_SELF;
        int ret;
 
-       ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
-       if (ret > 0)
-               max_pages = ret;
+       /*
+        * For the initial domain we use the maximum reservation as
+        * the maximum page.
+        *
+        * For guest domains the current maximum reservation reflects
+        * the current maximum rather than the static maximum. In this
+        * case the e820 map provided to us will cover the static
+        * maximum region.
+        */
+       if (xen_initial_domain()) {
+               ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
+               if (ret > 0)
+                       max_pages = ret;
+       }
        return min(max_pages, MAX_DOMAIN_PAGES);
 }
 


On Fri, Jan 13, 2012 at 09:15:32AM +0100, Florian Heigl wrote:
> Hi,
> 
> is this combination supposed to work?
> 
> Host kernel
> Linux waxh0015 3.0.14-grsec #1-Alpine SMP Thu Dec 22 10:31:30 UTC 2011
> x86_64 Linux
> 
> Xen Info:
> xen_major              : 4
> xen_minor              : 1
> xen_extra              : .2
> 
> 
> VM Kernel is:
> CentOS release 6.2 (Final)
> Kernel 2.6.32-220.2.1.el6.x86_64 on an x86_64
> 
> I was going to do a lot of tests today that would include hot-adding
> memory and cpus, and err, a recent distribution.
> 
> Anyone successfully ballooning CentOS 6.2?
> 
> Florian
> 
> -- 
> the purpose of libvirt is to provide an abstraction layer hiding all
> xen features added since 2006 until they were finally understood and
> copied by the kvm devs.
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users

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