On 28 July 2016 at 00:53, liubowen (A) <liubowen2@huawei.com> wrote:

Hi,

 

  Thanks for your time!

 

I am bob. I am interested in the CoreSight Project. And I get much from the web page http://www.linaro.org/blog/core-dump/coresight-perf-and-the-opencsd-library/.

 

Because I work on ARM64, there is a bug with perf working on ARM. Specific information from https://www.linaro.org/blog/core-dump/debugging-arm-kernels-using-nmifiq/.

 

  For instance, when we run : dd if=/dev/urandom of=/dev/null, over 90% of the CPU time is spent unlocking interrupts and the cryptographic operations that should dominate the

use case are completely hidden.

 

The author Daniel Thompson from Linaro comes up with a primary solution, however he suggests it will need further work.

 

Now, CoreSight can trace program flow only by hardware. If we combine coresight with perf, when we run “dd if=/dev/urandom of=/dev/null” and perf record, will the report be normal?   

  If it is normal, it will be amazing!!! And, I am eager for the related information.

 


What do you expect to see in a "normal" report?  

There is no restriction on the code CoreSight can trace, and with the soon-to-be released address filtering capabilities, knowing exactly what the HW is doing will become a lot easier.  The only requirement (for now) is that CPUidle be disabled.

 

  I have followed the documentation to enable coresight and perf, but get stuck. I can not figure out whether it is normal.


That is unfortunately the downside to CoreSight.  But as every powerful technology, complexity is inherent.
 

 

  I greatly appreciate for your help!!!    Thanks again for your time!!!



I am not sure of how I can help you here.  Other than the one above (to which I have replied), I don't see any specific questions.

Regards,
Mathieu
 


_______________________________________________
CoreSight mailing list
CoreSight@lists.linaro.org
https://lists.linaro.org/mailman/listinfo/coresight