For Advanced Hotspots, General Exploration and Custom event-based sampling analysis types on Linux* and Android* OS, you may not need root privileges and installing the sampling driver if your system is based on kernel 2.6.32 or higher, which exports CPU PMU programming details over /sys/bus/event_source/devices/cpu/format file system. This driverless sampling collection mode is based on the Linux Perf* functionality. VTune Amplifier automatically enables the driverless collection if the sampling driver cannot be installed with the product installation.
To resolve symbols for the Linux kernel, make sure you have enough permissions to read kernel symbol information from the /proc/kallsyms file. To do this, verify that the /proc/sys/kernel/kptr_restrict file contains values that enable reading /proc/kallsyms and providing non-zero addresses for the kernel symbols:
- If the
kptr_restrictvalue is 2, the kernel addresses are hidden regardless of privileges the current user has. - If the
kptr_restictvalue is 1, addresses are provided if the current user has aCAP_SYSLOGcapability. - If the
kptr_restrictvalue is 0, kernel addresses are provided without limitations.
See more details at: http://lwn.net/Articles/420403/, http://man7.org/linux/man-pages/man7/capabilities.7.html.
Limitations
Since the driverless collection is based on the Linux Perf functionality, all Perf limitations fully apply to the VTune Amplifier sampling analysis as well. For example, your operating system limits on the maximum amount of files opened by a process as well as maximum memory mapped to a process address space still apply and may affect Perf-based profiling. For more information, see the Tutorial: Troubleshooting and Tips topic at https://perf.wiki.kernel.org/index.php/Main_Page.
MRTE/JIT specific profiling is not supported.
Local and remote Launch Application, Attach to Process and Profile System target types are supported but this support fully depends on the Linux Perf profiling credentials specified in the
/proc/sys/kernel/perf_event_paranoidfile and managed by the administrator of your system using root credentials. For more information see the perf_event related configuration files topic at http://man7.org/linux/man-pages/man2/perf_event_open.2.html. By default, only user processes profiling at both user and kernel spaces is permitted, so you need granting wider profiling credentials via theperf_event_paranoidfile to employ the Profile System target type.For the driverless data collection, VTune Amplifier sampling drivers should be unloaded.