PageReserved ?

PageReserved ?

[aq]

hello,

here is my ballon information (domU)

#cat /proc/xen/balloon
Current allocation:    51200 kB
Requested target:      71680 kB
Low-mem balloon:           0 kB
High-mem balloon:          0 kB
Xen hard limit:          ??? kB


This looks a little bit strange to me: Low/High-mem is 0K, and that
indicates from 51200K up (Current allocation) to 70MB, all the pages
are reserved, which means I cannot balloon memory (?). Anybody knows
why so much memory are reserved?

Thank you,
aq

Re: PageReserved ?

[Keir Fraser]

On 15 Jul 2005, at 19:26, aq wrote:

> This looks a little bit strange to me: Low/High-mem is 0K, and that
> indicates from 51200K up (Current allocation) to 70MB, all the pages
> are reserved, which means I cannot balloon memory (?). Anybody knows
> why so much memory are reserved?

Add a 'mem=' line to your kernel command line (e.g., 'mem=100M' should 
work I think). That will ensure the domain makes itself a big enough 
memory map to increase its memory reservation.

  -- Keir

Re: PageReserved ?

[aq]

On 7/15/05, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:
> 
> On 15 Jul 2005, at 19:26, aq wrote:
> 
> > This looks a little bit strange to me: Low/High-mem is 0K, and that
> > indicates from 51200K up (Current allocation) to 70MB, all the pages
> > are reserved, which means I cannot balloon memory (?). Anybody knows
> > why so much memory are reserved?
> 
> Add a 'mem=' line to your kernel command line (e.g., 'mem=100M' should
> work I think). That will ensure the domain makes itself a big enough
> memory map to increase its memory reservation.

I still cannot create the "LowMem". Any suggestion? (I am running
latest -testing tree)

Here is my domain file:
--
kernel = "/boot/vmlinuz-2.6-xenU"
memory = 32
maxmem = 80
name = "tty"
disk = [ 'file:/home/aq/myxen/rootfs.tty,hda1,w' ]
root = "/dev/hda1 ro"
extra = "mem=150"
---

And here is domU's /proc/xen/balloon (immediately after creating domain):

 # cat /proc/xen/balloon 
Current allocation:    32768 kB
Requested target:      32768 kB
Low-mem balloon:           0 kB
High-mem balloon:          0 kB
Xen hard limit:          ??? kB


Thank you,
aq

Re: PageReserved ?

[Keir Fraser]

On 17 Jul 2005, at 08:30, aq wrote:

> extra = "mem=150"

Should be 150M.

You are currently specifying a limit of 150 bytes, which gets ignored 
by the guest when it boots.

  -- Keir

Re: PageReserved ?

[aq]

On 7/17/05, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:
> 
> On 17 Jul 2005, at 08:30, aq wrote:
> 
> > extra = "mem=150"
> 
> Should be 150M.
> 
> You are currently specifying a limit of 150 bytes, which gets ignored
> by the guest when it boots.

Too bad that I still have problem. My domain file is configured with
memory=32M, and maxmem=80M
--
kernel = "/boot/vmlinuz-2.6-xenU"
memory = 32
maxmem = 80
--

Then I tried extra mem: extra = "mem=xxxM" with xxx gets some value
under 32M, domain boots fine, but then I always got "Low-mem balloon:
0 kB"

With xxx > 32M, domain always failed to boot. 

Any suggestion now?

Thank you,
aq

Re: PageReserved ?

[Keir Fraser]

On 17 Jul 2005, at 10:40, aq wrote:

> Then I tried extra mem: extra = "mem=xxxM" with xxx gets some value
> under 32M, domain boots fine, but then I always got "Low-mem balloon:
> 0 kB"
>
> With xxx > 32M, domain always failed to boot.
>
> Any suggestion now?

It's probably been broken by the 2.6.12 upgrade. I'll look into it.

  -- Keir

Re: PageReserved ?

[aq]

On 7/17/05, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:
> 
> On 17 Jul 2005, at 10:40, aq wrote:
> 
> > Then I tried extra mem: extra = "mem=xxxM" with xxx gets some value
> > under 32M, domain boots fine, but then I always got "Low-mem balloon:
> > 0 kB"
> >
> > With xxx > 32M, domain always failed to boot.
> >
> > Any suggestion now?
> 
> It's probably been broken by the 2.6.12 upgrade. I'll look into it.

No, this is -testing tree (kernel 2.6.11.12)


Thank you,
aq

Re: PageReserved ?

[Keir Fraser]

On 17 Jul 2005, at 10:49, aq wrote:

>>> With xxx > 32M, domain always failed to boot.
>>>
>>> Any suggestion now?
>>
>> It's probably been broken by the 2.6.12 upgrade. I'll look into it.
>
> No, this is -testing tree (kernel 2.6.11.12)

I'd add xprintk's to the domU code (or turn printk into xprintk) and do 
a debug build of Xen. That'll get some early output from domU. Then you 
can work out how far it is getting and ultimately what line of code is 
failing.

   -- Keir

Re: PageReserved ?

[aq]

On 7/17/05, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:
> 
> On 17 Jul 2005, at 10:49, aq wrote:
> 
> >>> With xxx > 32M, domain always failed to boot.
> >>>
> >>> Any suggestion now?
> >>
> >> It's probably been broken by the 2.6.12 upgrade. I'll look into it.
> >
> > No, this is -testing tree (kernel 2.6.11.12)
> 
> I'd add xprintk's to the domU code (or turn printk into xprintk) and do
> a debug build of Xen. That'll get some early output from domU. Then you
> can work out how far it is getting and ultimately what line of code is
> failing.

ah, this is interesting. i will give it a try. lets see how to do that:

- you suggest adding xprintk to domU code - but exactly which code?
- or better redefine printk to xprintk in linux kernel of domU
(linux-2.6.x-xenU/)
- recompile xenU kernel (no need to recompile Xen and dom0 kernel).

is that correct?

thanks,
aq

Re: PageReserved ?

[Keir Fraser]

On 17 Jul 2005, at 11:48, aq wrote:

> ah, this is interesting. i will give it a try. lets see how to do that:
>
> - you suggest adding xprintk to domU code - but exactly which code?

Probably you are dying in pagetable_init() in arch/xen/i386/mm/init.c, 
but you could possibly be dying earlier than that.

> - or better redefine printk to xprintk in linux kernel of domU
> (linux-2.6.x-xenU/)
> - recompile xenU kernel (no need to recompile Xen and dom0 kernel).

You need to recompile Xen as 'debug=y make'. No need to recompile dom0.

> is that correct?