Re: [Xen-devel] Xen GCOV Patches for latest Xen Unbstable and linux 2.6.18.8 kernel(32/64bit)

[Tej <bewith.tej@gmail.com>]

On Mon, May 10, 2010 at 8:23 PM, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
> On Sat, May 08, 2010 at 01:31:01AM +0530, Tej wrote:
>> All,
>>
>> Here are the latest patches to expreiment with gcov profiler for xen
>> hypervisor. I have tested current patches on Intel i686.
>
> Nice..
>
>> System Details:
>> gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4)
>> gcov (Ubuntu 4.3.3-5ubuntu4) 4.3.3
>> Kernel 2.6.28-11-generic
>
> Uhh? 2.6.28 or 2.6.18?
>
> I hate to tell you this but development is happening in the pv-ops
> kernel, not anymore in the XenLinux branches :-(
>
> Any chance you can rebase those patches against the pv-ops kernel?
>
> Looking briefly at the Linux patches, you need to remove those #ifdef
> LINUX_VERSION_CODE, make the EXPORT_SYMBOL be EXPORT_SYMBOL_GPL, and
> also run the patch through scripts/checkpatch.pl

Thanks for your review/suggestion, will do all and get back but may be
after 2 weeks as i am off from the work, (only mails)

>> Distribution: Ubuntu jaunty 9.04
>>
>> There are some design issue which i would like to highlight here:
>> 1. To create gcov proc dir user /proc/xen, we are explicitly exported
>> xen_base symbol. I want to know your thoughts.
>> 2. XEN_GCOV_PROC config is set as not selected. So someone has to be
>> configured manually as M/Y
>>
>>
>> Known Issues:
>> File vmac.c throw some fault while using with lcov/gcov. This is due
>> to some raw count copy between xen and kernel. I could not able to
>> reproduce it many times, may be someone can try on 64 bit m/c.
>> "My take on this is that zero length array element in gcov_info
>> structure has to be copied separately between xen and kernel. How? I
>> dont know."
>>
>> I am still debugging this issue.
>>
>> If you get fault and fail to proceed please apply the above patch in
>> linux-wa-v1.patch in Linux 2.6.18.8 and recompile. This time vmac.gcda
>> file wont appear in /proc/xen/gcov/crypto
>>
>>
>> HOWTO Test using lcov
>> 1.  install lcov from repo
>>      # sudo apt-get install lcov
>> 2. vi /etc/lcovrc
>>     Change line: lcov_gcov_dir = /proc/gcov to lcov_gcov_dir = /proc/xen/gcov
>> 3. # cd  /tmp; lcov -c -o kernel.info
>> 4. # genhtml kernel.info
>> 5, # firefox index.html
>>
>> lcov README and screenshot is attached.
>
> 22% coverege, eh? Is that just by booting the Dom0 kernel?

Yes, but any operation on Xen which will reach to hypervisor is going
to change this number, since boot.

>
>>
>> HTH
>>
>> Note:
>> For any other detail required please CC me to parkash.tej@gmail.com
>
>> diff -r 86d6c6417cf9 drivers/xen/Kconfig
>> --- a/drivers/xen/Kconfig     Thu Feb 04 13:08:27 2010 +0000
>> +++ b/drivers/xen/Kconfig     Sun Feb 07 00:13:40 2010 +0530
>> @@ -311,6 +311,13 @@
>>       help
>>         Xen hypervisor attributes will show up under /sys/hypervisor/.
>>
>> +config XEN_GCOV_PROC
>> +       tristate "Code covarage for hypervisor"
>                          ^^^^^ - coverage

oops!!!!!! thanks for spotting the typo

>

-Tej