Intel Xeon Phi Coprocessor

timing is different each time

Hello ,

I wrote a simple application on cpu and I am using offload pragmas for the pieces I want to run on the coprocessors.

Since I am compiling on cpu and I use offloads , I am using :

<code>export MIC_ENV_PREFIX=MIC

in order to specify the threads number.

My problems:

1) Running the code , shows always 40 threads been used.

2) Running again and again the code without compiling , I am getting different time results.

What does __kmp_hierarchical_barrier_release imply in vTune?


I profiled my program running on Xeon Phi in native mode via vTune and realized that a lot of time goes to __kmp_hierarchical_barrier_release. What does this normally imply? I know it must be some OpenMP issue, but have no idea how to solve it.

BTW, the same piece of code, whening running on Xeon, vTune tells that some significant portion of time (much less than the __kmp_hierarchical_barrier_release in Phi though) goes to __kmp_launch_threads.

Thanks in advance!

Xeon Phi Power Management: Controlling C-states through Userspace


I have been trying to develop a runtime energy management library for Intel Xeon Phi using idle state control (C-states). I have read through a few blogs but I could not find answers to the following:

1. How can I implement control of C-states through userspace. Do I need to rebuild the MPSS service with userspace?

2. I have all power features enabled currently (cpufreq, corec6, pc3 and poc6). I can see the usage of the different idle states through

cat /sys/devices/system/cpu/cpu0/cpuidle/state*/usage (showing the usage of different cpuidle states??)

Overlay is not integrated into initrd (MPSS 3.4.2)


I just upgrade to the MPSS 3.4.2 and since filelists are not supported anymore for the base initrd, I tried the overlay feature with a filelist. However, I quickly realized that the files I wanted to add are not ending up in the final initrd image. So I investigated the problem and took a look at the final CPIO. What I found was the following structure:

Umounting nfs on MPSS, gives device/resource busy error, why ?


I am trying to use loopback device to access a file that contains a file system. I wrote a test and below are the steps that i tried manually from the test to debug the problem

Scenario  : I was trying nfs mount on my mic0 machine and while doing global umount i get an error. Steps below :

1) created a mount directory and mount nfs

mkdir /mnt/1

mount nfs on /mnt/1

2) Created two temporary(local) mount points and use them to mount the file. (say)

mkdir /tmp/p1

mkdir /tmp/p2

Iscriversi a Intel Xeon Phi Coprocessor