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Re: [Xen-devel] RE: [PATCH] Xenoprof passive domain support fixes

To: "Santos, Jose Renato G" <joserenato.santos@xxxxxx>
Subject: Re: [Xen-devel] RE: [PATCH] Xenoprof passive domain support fixes
From: "Ray Bryant" <raybry@xxxxxxxxxxxxxxxxx>
Date: Wed, 12 Jul 2006 13:40:10 -0500
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, "Yang, Xiaowei" <xiaowei.yang@xxxxxxxxx>
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Hi Renato,

On Tuesday 11 July 2006 15:51, Santos, Jose Renato G wrote:
>  Ray,

> >> Additionally, I find that "opreport -lx" will report "no symbols" for
> >> papps*-syms:
> >>
> >> samples  %        app name                 symbol name
> >> 76273    23.7738  papps2-syms              (no symbols)
> >> 19131     5.9630  pxen2-syms               l2e_rw_fault
> >> 17278     5.3854  jbd                      (no symbols)
> >> 12228     3.8114  ext3                     (no symbols)
> >> 11840     3.6905  libc-2.4.so              vfprintf
> >> 10256     3.1967  libc-2.4.so
> >> _IO_file_xsputn@@GLIBC_2.2.5
> >> 8587      2.6765  xen-syms                 general_protection
> >> 7374      2.2984  pxen2-syms               vmx_asm_vmexit_handler
> >> 5212      1.6245  pxen2-syms               resync_all
> >> 5128      1.5984  xen-syms                 write_cr3
> >> <snip>
> >>
> >> unless I do an "ln -s /boot/vmlinux2-syms
> >> /boot/papps2-syms".  (It appears that opreport should be
> >> creating papps2-syms instead of vmlinux2-syms??)
> papps2-syms represent samples collected in user level for domain2 (i.e.
> ring 3). Remember that passive domain profiling cannot decode
> application level samples since domain0 does not know the current memory
> mappings of user level processes in domain 2. Therefore it is expected
> that opreport will report "no symbols" for papps2-syms.

I see.  Oops.  :-)

> What is suspicious to me is that opreport is not reporting any samples
> in the kernel for domain2 (they should have appeared under the name
> vmlinux2-syms)

Perhaps you meant pvmlinux2-syms here?

> This is probably a bug. Maybe this is triggered if you do not specify
> the option --passive-images. Did you specify this option? If not, try
> running the command with --passive-images=<linux image file for xenU>
> (e.g. --passive-images=/boot/vmlinux-syms-2.6.16-xenU)

Yes, here is the setup script:

opcontrol --start-daemon --active-domains=0 --passive-domains=$passive \
        --passive-images=/home/raybry/RH4U2/vmlinux  \
        --xen=/home/raybry/xenbits-unstable.$cs.hg/xen/xen-syms \
        --verbose=all --event=GLOBAL_POWER_EVENTS:100000:1:1:1

where $cs is the current change set I am running and $passive is the passive 
domain id.

Of course, the actual image file for an HVM guest is stored in the / file 
system of the
guest, which in this case is a loopback mounted file.   So the vmlinux 
referenced above
is a copy of that file in the host's file system.

There are no samples attributed to pvmlinux2-syms in the oprofiled.log.   There 
lots of samples attributed to papps2-syms.   

Now this is all with your patches applied to change set 10428.  It's possible, 
I suppose,
that there are some subtle differences making this incorrect at that change set 
I'll move up to a more recent change set and try again.  Also, I "ported" your 
changes forward to 0.9.1, so I could have messed that up.  See the message I 
sent to Markus
on xen-devel for a copy of my version of your 

> >> Finally, I'm not convinced yet that the sample reports for
> >> the HVM guest (papps2-syms or pvmlinux2-syms, in this case)
> >> are correct.  I'm going to run some native and xen profile
> >> sessions using the same benchmark and see if I can correlate
> >> the results at all.
>  There is a problem with the current version of xenoprof for passive
> domains. Samples are being assigned to wrong samples. I posted a patch
> last week, that fix this problem but it seems that it was not pushed
> into the main unstable tree yet.
> Try applying that patch and check if they match what you get from
> native.
> (If you cannot find the patch, please let me know I will forward it to
> you)
> I would appreciate if you could send me the results of your tests,
> either if you find problems or if they are successfull. I think not many
> people have used passive domain support yet, and any feedback would be
> usefull.

I am running with your patches from 2006-07-07 3:15:15 for both xen and 
However, as stated above, I am running under changeset 10428.   Let me upgrade 
and try again.

> Thanks
> Renato

Thank you!

Best Regards,
Ray Bryant
AMD Performance Labs                   Austin, Tx
512-602-0038 (o)                 512-507-7807 (c)

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