Don’t use multiple runs with stack collection for event-based sampling

Problem:

VTune™ Amplifier XE 2013 supports new feature called “Call Stack Collection” for hardware PMU event-based sampling. However if the user set option “Allow multiple runs” in vtune’s project properties and enable “Call Stack Collection” option, to run some predefined analysis such as snb-general-exploration, snb-memory-access, etc. It will cause segmentation fail. Example command line:

# amplxe-cl -collect snb-general-exploration -knob enable-stack-collection=true -allow-multiple-runs -- /bin/ls

 

Message you will see:

Exception: 0xb, Segmentation fault

Module: libabstract.so

 

Root-cause:

The reason is that Call Stack Collection doesn't support Multiple Runs. When predefined analysis (or your defined analysis) includes many hardware events (>6), and option “-allow-multiple-runs” is enabled, this situation cannot support Call Stack Collection.

 

Solution:

Choose one of below options -

1.      Don’t use “-allow-multiple-runs”, use Event Multiplexing instead

2.      Disable Call Stack Collection, use option “-knob enable –stack-collection=false”

Einzelheiten zur Compiler-Optimierung finden Sie in unserem Optimierungshinweis.