Re: [Xen-devel] PV Memory allocated difference in kernel 2.6.18 and 3.2

[mad Engineer <themadengin33r@xxxxxxxxx>]

Ian,
    I suggested you try a 3.2 based SusE forward port kernel, of whichÂUbuntu's 2.6.32 is neither. I'm afraid you are comparing apples toÂoranges still.  Â

Â

         ÂWhy Âi posted Ubuntu with 2.6 kernel is i thought that it would be fair comparing kernels that are 2.6+ ,more over i don't have any distros other than Ubuntu with 3+ kernel in this environment.Â

My intention is not Âto compare 2.6 with 3.0 as i said i noticed the difference on distros running these kernels.Â

How are you defining wastage here?

i dont know whether wastage is the correct term,what i mean is amount of memory that's installed to what is actually available in "free -m" (i'm aware about kernel/user split but that seems to be not applicable in case of distros with kernel Â<2.6.32) .This is what i am trying to figure out.

today i tried redhat 5.7,5.10 (2.6.18+) and 6.0 (2.6.32)

out of this redhat 5.7,5.10 all shows same amount of memory as assigned from XenÂ

redhat6.0

         xentop

        ÂNAME ÂSTATE  CPU(sec)   CPU(%)   ÂMEM(k)   MEM(%)  ÂMAXMEM(k)  Â

          red6  --b---    Â194         Â1.4       524288   25.4      Â525312    ÂÂ

        Inside guest

             ÂÂ

          free -k

                       total    used       Âfree   shared  Âbuffers   cached

             Mem:    Â502224   122064   380160     Â0    7636   Â32648

redhat 5.10

        Âxentop

       NAME    STATE  CPU(sec)   CPU(%)   ÂMEM(k)   MEM(%)  ÂMAXMEM(k)  ÂÂÂ

        Âred510  Â--b---     14         Â0.0       524288  Â25.4      Â525312

ÂÂ Inside guest

      Â

         free -k

                        total    used    free      shared  Âbuffers   cached

            Mem:    Â524288   399072  125216     Â0      80188   164404

So in case of 5.7 and 5.10 which is using 2.6.18 kernel available memory=installed memoryÂ

but on Ubuntu10.04 (downloaded xen kernel in classical way) and RHEL 6.0(used default kernel) which is using 2.6.32 kernel available memory != installed memory

Does this difference has any thing to do with Xen support in upstream kernel

This is what i was trying to explain and i hope at least my motive is clear :)

i already started with open suse 12.3 haven't yet checked thisÂ

Thanks

On Wed, May 28, 2014 at 3:08 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

On Tue, 2014-05-27 at 00:48 +0530, mad Engineer wrote:
> Thanks Ian,
>
> i think i started noticing the difference on centos 5.7(2.6.18) and
> Ubuntu 12.04 (3.2.0-48) thats why i posted that.
>
>
> Now as per you suggestion i created ubuntu 10.04 which is
> 2.6.32-60-generic

I suggested you try a 3.2 based SusE forward port kernel, of which
Ubuntu's 2.6.32 is neither. I'm afraid you are comparing apples to
oranges still.

> so now the comparison is between 2.6.18 and 2.6.32 but on different
> distros,not sure whether i can compare both.

>

> Centos 5.7 is showing Zero wastage of RAM but ubuntu shows a slight
> difference. of ~19MB,where as ubuntu 12.04 shows a difference of ~23
> Mb.

How are you defining wastage here?

Ian.

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