* Mapping of Shared Page in e500 Powerpc kvm
@ 2011-10-23 13:45 Aashish Mittal
2011-10-23 15:14 ` Alexander Graf
2011-10-25 20:38 ` Scott Wood
0 siblings, 2 replies; 3+ messages in thread
From: Aashish Mittal @ 2011-10-23 13:45 UTC (permalink / raw)
To: kvm-ppc
Hi
I'm working on powerpc e500 machine (Freescale P2020RDB machine) and
using the paravirtualization guest support available inside kvm and wanted
to some bookkeeping of my own on the shared page and from what i
understood is that a single tlb entry is reserved for the shared page
(magic page) when running the guest which is never preempted or flushed
but when i tried printing out the dtlb misses on this shared page it show
me a large number of dtlb misses on this shared page which means that
this page is being preempted or flushed out in some way . Can someone pleas
e clarify this situation if i'm understanding something wrong or is it a bug ?
Thanks
Aashish Mittal
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Mapping of Shared Page in e500 Powerpc kvm
2011-10-23 13:45 Mapping of Shared Page in e500 Powerpc kvm Aashish Mittal
@ 2011-10-23 15:14 ` Alexander Graf
2011-10-25 20:38 ` Scott Wood
1 sibling, 0 replies; 3+ messages in thread
From: Alexander Graf @ 2011-10-23 15:14 UTC (permalink / raw)
To: kvm-ppc
Am 23.10.2011 um 15:45 schrieb Aashish Mittal <aashish.mittal4u@gmail.com>:
> Hi
>
> I'm working on powerpc e500 machine (Freescale P2020RDB machine) and
> using the paravirtualization guest support available inside kvm and wanted
> to some bookkeeping of my own on the shared page and from what i
> understood is that a single tlb entry is reserved for the shared page
> (magic page) when running the guest which is never preempted or flushed
> but when i tried printing out the dtlb misses on this shared page it show
> me a large number of dtlb misses on this shared page which means that
> this page is being preempted or flushed out in some way . Can someone pleas
> e clarify this situation if i'm understanding something wrong or is it a bug ?
We have seen similar effects and concluded it to be a bug, but didn't track down what exactly was causing it yet.
Alex
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Mapping of Shared Page in e500 Powerpc kvm
2011-10-23 13:45 Mapping of Shared Page in e500 Powerpc kvm Aashish Mittal
2011-10-23 15:14 ` Alexander Graf
@ 2011-10-25 20:38 ` Scott Wood
1 sibling, 0 replies; 3+ messages in thread
From: Scott Wood @ 2011-10-25 20:38 UTC (permalink / raw)
To: kvm-ppc
On 10/23/2011 08:45 AM, Aashish Mittal wrote:
> Hi
>
> I'm working on powerpc e500 machine (Freescale P2020RDB machine) and
> using the paravirtualization guest support available inside kvm and wanted
> to some bookkeeping of my own on the shared page and from what i
> understood is that a single tlb entry is reserved for the shared page
> (magic page) when running the guest which is never preempted or flushed
> but when i tried printing out the dtlb misses on this shared page it show
> me a large number of dtlb misses on this shared page which means that
> this page is being preempted or flushed out in some way . Can someone pleas
> e clarify this situation if i'm understanding something wrong or is it a bug ?
What kernel are you running, and how many is "a large number"?
The magic page TLB entry will need to be reloaded if the shadow PID gets
invalidated, another guest gets scheduled on that CPU, or if something
like hugetlbfs steps on that TLB entry.
If you're running a kernel that predates shadow PID support, it will be
invalidated (along with everything else in the TLB) whenever you
schedule out or change guest execution mode .
-Scott
^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-10-23 13:45 Mapping of Shared Page in e500 Powerpc kvm Aashish Mittal
2011-10-23 15:14 ` Alexander Graf
2011-10-25 20:38 ` Scott Wood
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