Xen devel - Apr 2011 - Memory sharing

Hi,

Currently i''m going through the source codes of tools/blktap2. I need
to
find-out where blktap2 calls
1. mem_share_nominate()
2. mem_sharing_share_page() functions to do the memory sharing on HVM
guests.

Can someone please provide me some guidance on blktap2 driver.

Thanks,
Harshan


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On 03/04/2011 09:28, "Lakshitha Harshan" <harshan.dll@gmail.com>
wrote:
> Hi,
> 
> Currently i''m going through the source codes of tools/blktap2. I
need to
> find-out where blktap2 calls 
> 1. mem_share_nominate()
> 2. mem_sharing_share_page() functions to do the memory sharing on HVM
guests.
Use recursive grep or similar to find uses of those functions in Xen. Find
out what DOMCTL command they are associated with, search for that in similar
way in tools/libxc directory, search for uses of the libxc interface
function elsewhere in tools/, and so on.

You''ll find mem_sharing_share_page will take you from Xen to
tools/libxc to
tools/memshr to tools/blktap2.

find . -name ''*.c'' | xargs grep -n <word_to_search_for>

 -- Keir
> Can someone please provide me some guidance on blktap2 driver. 
> 
> Thanks,
> Harshan 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


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Hi guys,

I''m receiving following errors when trying to create a VM.

Error: Failed to create device.
    stdout:
    stderr: MEMSHR support not compiled in.
Check that target "home/images/ubuntuX.img" exists and that blktap2
driver
installed in dom0.

In configuration file this is how i specify my disks.

 disk = [''tap2:tapdisk:aio:home/images/ubuntuX.img,hda,w'',
''phy:/dev/sr0,hdc:cdrom,r'' ]

But if I use
 tapdisk2  -n aio:/home/images/ubuntuX.img  command it executes and returns
"/dev/xen/blktap-2/tapdev0".

What I want is to test the memory sharing feature. So can anybody tell me
how to do that?
Thanks,
Harshan


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On 09/04/2011 07:37, "Lakshitha Harshan" <harshan.dll@gmail.com>
wrote:
> Hi guys,
> 
> I''m receiving following errors when trying to create a VM.
> 
> Error: Failed to create device.
>     stdout: 
>     stderr: MEMSHR support not compiled in.
> Check that target "home/images/ubuntuX.img" exists and that
blktap2 driver
> installed in dom0.
> 
> In configuration file this is how i specify my disks.
> 
>  disk =
[''tap2:tapdisk:aio:home/images/ubuntuX.img,hda,w'',
> ''phy:/dev/sr0,hdc:cdrom,r'' ]
> 
> But if I use
>  tapdisk2  -n aio:/home/images/ubuntuX.img  command it executes and returns
> "/dev/xen/blktap-2/tapdev0". 
> 
> What I want is to test the memory sharing feature. So can anybody tell me
how
> to do that?
You could try reverting changeset 20927:b882c558d4e4 and cross your fingers.
Looks like blktap2 devs disabled memshr extensions due to them not working
properly.

 -- Keir
> Thanks,
> Harshan
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


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Hi,

I''m trying to create a code which invokes xc_memshr_nominate_gfn() and
xc_memshr_share().

In my testing code I use,

uint64_t handle; int y;
y = xc_memshr_nominate_gfn(xc_handle,dom,1500,&handle);

It returns -1 even if I use another gfn number instead of 1500. So my
question is why does i returns -1 every time. My guest VMs are HVM (64-bit),
PAE & HAP enabled. I''m using Xen-4.0.2-rc3.

Is it  possible to use these memory sharing functions in this manner
 without any support from blktap2?

If someone could provide me some sample code on how to invoke this functions
it would be a great help to me.

Thanks,
Harshan


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Hi all,

I''m doing some tests on memory sharing feature. Current version
i''m having
is not working (Xen -4.0.2-rc3 on Debian Dom0 (linux 2.6.32.27)).

So can anybody please send me the details of working configuration?

Thanks,
Harshan


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Hi, 

At 05:49 +0100 on 03 May (1304401799), Lakshitha Harshan
wrote:
> I''m doing some tests on memory sharing feature. Current version
i''m
> having is not working (Xen -4.0.2-rc3 on Debian Dom0 (linux
> 2.6.32.27)).
That''s a very old version of Xen.  I don''t use memory sharing,
and maybe
someone who does can suggest a better starting point, but I would
suggest using at least the tip of 4.1-testing, and the Debian packaged
dom0 kernel.

Tim.

-- 
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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