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

To: burke@xxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Memory squeeze in netback driver?
From: Jason Dillon <jason@xxxxxxxxxxxx>
Date: Thu, 3 May 2007 16:25:13 -0700
Cc: Adam Jacob <adam@xxxxxxxxxxxxxxxx>, Xen Users <xen-users@xxxxxxxxxxxxxxxxxxx>
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I've not tried setting dom0_min_mem, this is also a kernel param? Any suggestions on what that size should be?

--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


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