Problem accessing the sampling driver. The driver may need to be (re)started...

This error message is an indication of Intel® VTuneTM Amplifier XE not being able to access the hardware event-based sampling (EBS) driver when lightweight hotspot (or any other event based sampling analysis types) is selected.  This problem happens due to EBS driver not being loaded or due to user not having correct permissions.

By default the EBS driver access group is ‘vtune' and the user trying to use any of the EBS analysis types such as Lightweight Hotspot must be member of the ‘vtune' group. If you are not part of the ‘vtune' group then please add your user name to the ‘vtune' group by editing /etc/group file or contact your system administrator.

Checklist:

  • Make sure the EBS drivers are loaded
    • lsmod | grep sep3_1
    • lsmod | grep pax
  • If the drivers are already loaded then make sure you are a member of the ‘vtune' user group. You can check /etc/group file or contact your system administrator to find out if you are a member of the group or not.

If you are still getting the same error message then please check if the correct sampling driver is available for your kernel version. You can check the pre-built drivers located at /opt/intel/vtune_amplifier_xe_2011/sepdk/prebuilt.

If there is no matching driver for your kernel version and if the driver was not built during the installation, you can try to build the driver yourself and then load it manually.

  • cd /opt/intel/vtune_amplifier_xe_2011/sepdk/src/
  • Build the drivers: ./build-driver
  • Load the drivers: ./insmod-sep3
    Note:
    Please check out README.txt located under /opt/intel/vtune_amplifier_xe_2011/sepdk/src/ to find out more about building and loading the driver.

By default /opt/intel/vtune_amplifier_xe_2011/sepdk/src/insmod-sep3 script performs the following:

Checking for PMU arbitration service (PAX) ... detected.

PAX service is accessible to users in group "vtune".

Executing: insmod ./sep3_1-x32_64-2.6.27.19-5-defaultsmp.ko

Creating /dev/sep3_1 base devices with major number 247 ... done.

Creating /dev/sep3_1 percpu devices with major number 246 ... done.

Setting group ownership of devices to group "vtune" ... done.

Setting file permissions on devices to "660" ... done.

The sep3_1 driver has been successfully loaded.

As you can see from the output, the driver is accessible to the users in 'vtune' group and the device permissions are set to 660. If you like to restrict access to user groups other than 'vtune' you can do that with -g option.

Please see the insmod-sep3 options:

Usage: ./insmod-sep3 [ options ]

where "options" are the following:

-g | --group
group restricts access to the sep3_1 driver to users in the specified group; if this option is not provided, the group "vtune" will be used


-p | --perms 
fileperms restricts access to the sep3_1 driver based on the specified file permissions; if this option is not provided, then file permissions "660" (or equivalently, "ug+rw") will be used


-q | --query 
returns 0 if driver is already loaded, non-zero otherwise; if driver is loaded, information on group ownership and file permissions on driver device will be displayed


-r | --reload
attempt to reload all relevant drivers; note that drivers will not unload if they are still in use

 
Note: Many of the VTune™ Amplifier XE profiling features will work with a non-root install on either a genuine Intel processor or a compatible processor. But the drivers for EBS data collection require root privileges for install, a genuine Intel processor and a non-virtual OS. EBS analysis makes use of the on chip Performance Monitoring Unit (PMU) and requires a genuine Intel processor for collection. EBS drivers can be installed later by your administrator if you do not have root privileges. For more details, please see the release notes.

 

Para obtener más información sobre las optimizaciones del compilador, consulte el aviso sobre la optimización.