Re: [Xen-users] Exactly set dom0/U memory, increase vcpu count

[Jan Hejl <jh@xxxxxxxxxx>]

Hi Michal,

1) Could you please post your dom0 kernel config options related to XEN? 
Simply with "zgrep XEN /proc/config.gz" or "grep XEN 
/usr/src/linux/.config" ?
2) Is CONFIG_HOTPLUG_CPU enabled in your kernel image?

Thanks
Jan

On 03/04/2013 06:23 PM, Michal Fiala wrote:
> hallo,
>
> I have updated xen server to
>
> xen-4.2.1-r2
> xen-tools-4.2.1-r1
> kernel gentoo-sources-3.2.39
>
> I have found 2 problems
>
> 1) Can not exactly set dom0, domU memory
>
> I dedicate 4G of memory to dom0 via kernel parameter:
>
> dom0_mem=4G,max:4G dom0_max_vcpus=4 dom0_vcpus_pin
>
> Bud the real total memory is set to 2618M after reboot. I have found
> article describing this behavior
> (http://wiki.xen.org/wiki/Do%EF%BB%BFm0_Memory_%E2%80%94_Where_It_Has_Not_Gone),
> so I have run
>
> echo $((4*1024*1024)) > /sys/devices/system/xen_memory/xen_memory0/target_kb
>
> The total memory was se to 3687M. This is better, but not enough.
>
> I have tested kernel 3.7, there is not such problem. I would like to use
> longterm kernel 3.2 so I would like to stay with 3.2.
>
> Similar problem exists with domU, config looks like
>
> kernel = '/etc/xen/kernels/linux-3.2.39-gentoo'
> name   = 'test1'
> memory = '4000'
> maxmem = '12000'
> vcpus  = '8'
> cpus   = '^0,^1,^2,^3'
> extra  = 'elevator=noop gentoo=nodevfs'
> root   = '/dev/xvda1 ro'
> disk   = [
>                'phy:/dev/vg1/test1_root,xvda1,w',
>                'phy:/dev/vg1/test1_var,xvda2,w',
>           ]
> vif    = [
>                'mac=00:16:3e:24:11:38,bridge=br0',
>           ]
>
> After boot, test1 domain has 3704M total memory (free -m), xm list test1
> shows 4000M.
>
> When I increase memory amount via xm mem-set test1 8000, then xm list
> test1 really shows 8000M, but domU has 7704M total memory (free -m).
>
> from xend.log
> [2013-03-04 18:10:18 4627] DEBUG (XendDomainInfo:1467) Setting memory
> target of domain test1 (1) to 8000 MiB.
>
> 2) I am not able to increase vcpu count to domU.
> After boot domU test1, it has really 8 vcpus, I am able to decrease
> vcpus by xm vcpu-set test1 4. Cpus count inside test1 really decreases
> to 4. Now I would like to increase vcpu count via xm vcpu-list test1 6,
> but unsuccessfully.
>
> rajvir3 configs # xm vcpu-list test1
> Name                                ID  VCPU   CPU State   Time(s) CPU
> Affinity
> test1                                1     0    15   -b-       3.7 12-23
> test1                                1     1    23   -b-       2.8 12-23
> test1                                1     2    18   -b-       1.2 12-23
> test1                                1     3    20   -b-       1.2 12-23
> test1                                1     4    16   -b-       1.0 12-23
> test1                                1     5    12   -b-       3.5 12-23
> test1                                1     6    19   -b-       0.9 12-23
> test1                                1     7    14   -b-       0.9 12-23
>
> rajvir3 configs # xm vcpu-set test1 4
>
> rajvir3 configs # xm vcpu-list test1
> Name                                ID  VCPU   CPU State   Time(s) CPU
> Affinity
> test1                                1     0    15   -b-       3.7 12-23
> test1                                1     1    23   -b-       2.9 12-23
> test1                                1     2    18   -b-       1.3 12-23
> test1                                1     3    20   -b-       1.2 12-23
> test1                                1     4     -   --p       1.0 12-23
> test1                                1     5     -   --p       3.5 12-23
> test1                                1     6     -   --p       1.0 12-23
> test1                                1     7     -   --p       0.9 12-23
>
> rajvir3 configs # xm vcpu-set test1 6
>
> rajvir3 configs # xm vcpu-list test1
> Name                                ID  VCPU   CPU State   Time(s) CPU
> Affinity
> test1                                1     0    15   -b-       3.8 12-23
> test1                                1     1    23   -b-       2.9 12-23
> test1                                1     2    18   -b-       1.3 12-23
> test1                                1     3    20   -b-       1.3 12-23
> test1                                1     4     -   --p       1.0 12-23
> test1                                1     5     -   --p       3.5 12-23
> test1                                1     6     -   --p       1.0 12-23
> test1                                1     7     -   --p       0.9 12-23
>
> from xend.log
>
> [2013-03-04 18:12:58 4627] INFO (XendDomainInfo:1978) Set VCPU count on
> domain test1 to 4
> [2013-03-04 18:14:51 4627] INFO (XendDomainInfo:1978) Set VCPU count on
> domain test1 to 6
>
> I was not able to increase vcpu count also in kernel 3.7.
>
> Where could be the problem?
>
> Thanks
>
> Michal
>
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> http://lists.xen.org/xen-users

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