Re: [Xen-users] Memory squeeze in netback driver?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I've not tried setting dom0_min_mem, this is also a kernel param?
> Any suggestions on what that size should be?

It's a setting in /etc/xen/xend-config.sxp.  Set it to something reasonable to 
make sure that dom0 doesn't get ballooned down too far.  I think for a 
production machine a sensible measure would be to set dom0-min-mem=0 to 
disable auto-ballooning entirely - then set dom0_mem on the Xen command line.

On my test box where I run up to about 3-4 domUs, not heavily loaded, I have 
been running with dom0-min-mem=196M and dom0_mem=256M.  I should probably 
just disable ballooning altogether on this machine.

A static dom0 memory allocation should really be just fine on a server, the 
auto-ballooning is more useful for desktop use or for playing around and 
getting the feel of things without having to reconfigure manually all the 
time.

Cheers,
Mark

> --jason
>
> On May 3, 2007, at 4:03 PM, Ryan Burke wrote:
> >> Is there any rule for how much memory dom0_mem should be set to?
> >> I've got 16g in this machine, and run ~12 1g domU's.
> >>
> >> Is more memory for dom0_mem better?  or is less better?
> >>
> >> --jason
> >>
> >> On May 3, 2007, at 8:14 AM, Adam Jacob wrote:
> >>> On Thu, May 03, 2007 at 03:03:43AM -0700, Jason Dillon wrote:
> >>>> I've been running into this from time to time... usually when xm
> >>>> creating a new domU, /var/log/messages for dom0 spits out:
> >>>>
> >>>> <snip>
> >>>> May  3 02:56:04 tweak kernel: printk: 4 messages suppressed.
> >>>> May  3 02:56:04 tweak kernel: xen_net: Memory squeeze in netback
> >>>> driver.
> >>>> </snip>
> >>>>
> >>>> And at this point all of the network connectivity for *all* domU's
> >>>> controlled for that dom0 vanish.  I have to xm shutdown and xm
> >>>> create
> >>>> them again to get the network back.  This doesn't happen all of the
> >>>> time, seems rather random really.
> >>>>
> >>>> Its *really* annoying.  Is there a way to prevent this from
> >>>> happening?
> >>>
> >>> You need to set the dom0_mem parameter at boot time.  Something
> >>> like:
> >>>
> >>> kernel          /xen-3.0.3-1-amd64.gz dom0_mem=256M
> >>>
> >>> Has been working for us.
> >>>
> >>> Adam
> >
> > Have any of you tried setting the dom0_min_mem variable? I had this
> > problem back in 3.0.2 and if I remember right the solution was to set
> > dom0_min_mem so that there wasa minimum that Dom0 would balloon
> > down. I
> > think that fixed it.
> >
> > Ryan
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users



-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users