What is a good value for dom0_mem if I want to start X server and run GNOME?
Will 512 MB be too little?

-- 
Mr. Teo En Ming (Zhang Enming) Dip(Mechatronics) BEng(Hons)(Mechanical
Engineering)
Alma Maters:
(1) Singapore Polytechnic
(2) National University of Singapore
My Primary Blog: http://teo-en-ming-aka-zhang-enming.blogspot.com
My Secondary Blog: http://enmingteo.wordpress.com
My Youtube videos: http://www.youtube.com/user/enmingteo
Email: space.time.universe@gmail.com
Mobile Phone (Starhub Prepaid): +65-8369-2618
Street: Bedok Reservoir Road
Country: Singapore

On Mon, Nov 9, 2009 at 8:05 PM, Pasi Kärkkäinen <pasik@iki.fi> wrote:

> On Mon, Nov 09, 2009 at 08:01:00PM +0800, Mr. Teo En Ming (Zhang Enming)
> wrote:
> >    No, I didn't limit dom0 memory in grub.conf.
> >
>
> You should.
>
> If dom0 has all the memory at boot time, you need to balloon down dom0
> memory every time you create a new guest - this can (and will) cause
> problems with the dom0 linux kernel.
>
> Linux calculates some internal parameters/buffers/values based on the
> _boot time_ amount of memory. And when the amount of memory goes down to
> only a small fraction of that while creating new guests bad things can
> happen..
>
> It still shouldn't crash though.. I bet your problem will get fixed when
> you limit the dom0 memory to say dom0_mem=512M and reboot.
>
> -- Pasi
>
> >    Here's my xm info output after I have shutdown all the virtual
> machines.
> >
> >    [root@fedora11-x86-64-host ~]# xm list
> >    Name                                        ID   Mem VCPUs      State
> >    Time(s)
> >    Domain-0                                     0  2812     2     r-----
> >    3242.5
> >    [root@fedora11-x86-64-host ~]# xm info
> >    host                   : fedora11-x86-64-host
> >    release                : 2.6.30-rc3-enming.teo-tip
> >    version                : #1 SMP Wed Aug 19 23:14:15 SGT 2009
> >    machine                : x86_64
> >    nr_cpus                : 2
> >    nr_nodes               : 1
> >    cores_per_socket       : 2
> >    threads_per_core       : 1
> >    cpu_mhz                : 2800
> >    hw_caps                :
> >
>  bfebfbff:20100800:00000000:00000140:0400e3bd:00000000:00000001:00000000
> >    virt_caps              : hvm hvm_directio
> >    total_memory           : 6039
> >    free_memory            : 3124
> >    node_to_cpu            : node0:0-1
> >    node_to_memory         : node0:3124
> >    xen_major              : 3
> >    xen_minor              : 5
> >    xen_extra              : -unstable
> >    xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
> >    hvm-3.0-x86_32p hvm-3.0-x86_64
> >    xen_scheduler          : credit
> >    xen_pagesize           : 4096
> >    platform_params        : virt_start=0xffff800000000000
> >    xen_changeset          : Tue Sep 01 11:34:31 2009 +0100
> 20143:a7de5bd776ca
> >    xen_commandline        : iommu=1
> >    cc_compiler            : gcc version 4.4.1 20090725 (Red Hat 4.4.1-2)
> >    (GCC)
> >    cc_compile_by          : root
> >    cc_compile_domain      : (none)
> >    cc_compile_date        : Thu Sep 10 07:01:13 SGT 2009
> >    xend_config_format     : 4
> >
> >    --
> >    Mr. Teo En Ming (Zhang Enming) Dip(Mechatronics) BEng(Hons)(Mechanical
> >    Engineering)
> >    Alma Maters:
> >    (1) Singapore Polytechnic
> >    (2) National University of Singapore
> >    My Primary Blog: [1]http://teo-en-ming-aka-zhang-enming.blogspot.com
> >    My Secondary Blog: [2]http://enmingteo.wordpress.com
> >    My Youtube videos: [3]http://www.youtube.com/user/enmingteo
> >    Email: [4]space.time.universe@gmail.com
> >    Mobile Phone (Starhub Prepaid): +65-8369-2618
> >    Street: Bedok Reservoir Road
> >    Country: Singapore
> >
> >    On Mon, Nov 9, 2009 at 7:54 PM, Pasi Kärkkäinen <[5]pasik@iki.fi>
> wrote:
> >
> >      On Mon, Nov 09, 2009 at 06:52:37PM +0800, Mr. Teo En Ming (Zhang
> Enming)
> >      wrote:
> >      >    Hi,
> >      >
> >      >    Please watch this 4-minute video at
> >      >    [1][6]http://www.youtube.com/watch?v=LbLaPpwNAx4
> >      >
> >      >    I have only started 3 HVM Linux guests with 1 GB ram each. I
> can't
> >      start
> >      >    the 4th HVM guest. If I attempt to start the 4th instance, it
> will
> >      crash
> >      >    dom0.
> >      >
> >      >    Are there anything in the xm dmesg output that could explain
> the
> >      low limit
> >      >    to the number of VMs that I could start before dom0 becomes
> >      unresponsive?
> >      >
> >
> >      Have you limited dom0 memory (by specifying dom0_mem=XMB option in
> >      grub.conf for xen.gz) ?
> >
> >      What does "xm info" say about free memory before starting any
> guests?
> >      -- Pasi
> >
> > References
> >
> >    Visible links
> >    1. http://teo-en-ming-aka-zhang-enming.blogspot.com/
> >    2. http://enmingteo.wordpress.com/
> >    3. http://www.youtube.com/user/enmingteo
> >    4. mailto:space.time.universe@gmail.com
> >    5. mailto:pasik@iki.fi
> >    6. http://www.youtube.com/watch?v=LbLaPpwNAx4
>