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

[Alex Williams <awilliams@xxxxxxxx>]

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/

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