WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] Possible regression: XEN 4.0.0 total_memory decrease

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Possible regression: XEN 4.0.0 total_memory decrease
From: Alex Williams <awilliams@xxxxxxxx>
Date: Thu, 15 Apr 2010 14:26:42 -0400
Cc: "Xen-devel@xxxxxxxxxxxxxxxxxxx" <Xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Thu, 15 Apr 2010 11:27:18 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C7ED13EA.1174E%keir.fraser@xxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <C7ED13EA.1174E%keir.fraser@xxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Thunderbird 2.0.0.24 (Macintosh/20100228)
Yes you're correct! Both hosts have dom0_mem=512M set.

Xen 3.4.2: free_memory            : 3514
Xen 4.0.0: free_memory            : 3523

So now it appears to be a free memory INCREASE caused by this 'bug' ? ;)

Thank you!!!


Keir Fraser wrote:
Ah, hm, I think this is a bug in total memory reporting only. I think the
memory is still there in the free pools though. :-) How does xm info's
free_memory compare in the two cases? I bet it's a lot closer than 150MB
(assuming dom0 is allocated the same amount of memory in both cases, e.g.,
by explicitly specifying dom0_mem=xxx on Xen command line).

 -- Keir

On 15/04/2010 18:33, "Alex Williams" <awilliams@xxxxxxxx> wrote:

Hello,

Both builds run a 64-bit Xen kernel and 64-bit Dom0 kernel.

(XEN)  Xen  kernel: 64-bit, lsb, compat32
(XEN)  Dom0 kernel: 64-bit, lsb, paddr 0xffffffff80200000 ->
0xffffffff805d388c

As for the RAM:

Xen 3.4.2: (XEN) System RAM: 3946MB (4041012kB)
Xen 4.0.0: (XEN) System RAM: 4084MB (4182064kB)

I have also verified with only 2048MB installed in the system. Here are
the results:

Xen 3.4.2: (XEN) System RAM: 2036MB (2084912kB)
Xen 4.0.0: (XEN) System RAM: 1898MB (1943860kB)

Still 150MB RAM missing... it appears this problem is static and
independant of the amount of RAM installed in the system.

Regards,



Keir Fraser wrote:
Are the hypervisor and dom0 kernel 64-bit or 32-bit? Xen prints a message
"System RAM: xxx" early during boot. Do these differ significantly for you
between 3.4.2 and 4.0.0?

 K.

On 15/04/2010 16:54, "Alex Williams" <awilliams@xxxxxxxx> wrote:

Hello,

I noticed a significant *decrease* (150MB) in "total_memory" on a host
build using XEN 4.0.0 with kernel 2.6.18.

Here are the details:

Server = 4096MB RAM
XEN 3.4.2 + kernel 2.6.18: xm info | grep total_memory = 4084
XEN 4.0.0 + kernel 2.6.18: xm info | grep total_memory = 3946

The exact same kernel config file was used for both builds. I also made
sure there is absolutely no difference on the hosts (while the builds
are created on a different machine).

This seems like a regression, unless someone can provide suggestions on
how to correct this?

Thanks.


--
Alexander Williams
IT Architecture Specialist
Spécialiste de l'Architecture TI
http://www.iWeb.com/

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