Before you can start profiling cache behavior with Arm SPE and Perf C2C, your system needs to meet a few requirements. In this section, you’ll learn how to check whether your hardware and kernel support Arm SPE, install the necessary tools, and validate that Linux Perf can access the correct performance monitoring events. By the end, your environment will be ready to record and analyze memory access patterns using perf c2c on an Arm Neoverse system.
SPE requires support from both your hardware and the operating system. Many cloud instances running Linux do not enable SPE-based profiling.
You need to identify a system that supports SPE using the information below.
If you are looking for an AWS system, you can use a c6g.metal instance running Amazon Linux 2023 (AL2023).
Check the underlying Neoverse processor and operating system kernel version with the following commands:
lscpu | grep -i "model name"
uname -r
The output includes the CPU type and kernel release version:
Model name: Neoverse-N1
6.1.134-152.225.amzn2023.aarch64
Next, install the prerequisite packages using the package manager:
sudo dnf update -y
sudo dnf install perf git gcc cmake numactl-devel -y
Linux Perf is a userspace process and SPE is a hardware feature. The Linux kernel must be compiled with SPE support or the kernel module named arm_spe_pmu must be loaded.
Run the following command to confirm if the SPE kernel module is loaded:
sudo modprobe arm_spe_pmu
If the module is not loaded (and there is blank output), SPE might still be available.
Run this command to check if SPE is included in the kernel:
ls /sys/bus/event_source/devices/ | grep arm_spe
If SPE is available, the output you will see is:
arm_spe_0
If the output is blank then SPE is not available.
You can install and run a Python script named Sysreport to summarize your system’s performance profiling capabilities.
See the Learning Path Get ready for performance analysis with Sysreport to learn how to install and run it.
Look at the Sysreport output and confirm SPE is available by checking the perf sampling field.
If the printed value is SPE, then SPE is available.
...
Performance features:
perf tools: True
perf installed at: /usr/bin/perf
perf with OpenCSD: False
perf counters: 6
perf sampling: SPE
perf HW trace: None
perf paranoid: -1
kptr_restrict: 0
perf in userspace: disabled
Run the following command to confirm SPE is available to perf:
sudo perf list "arm_spe*"
You should see the output below indicating the PMU event is available.
List of pre-defined events (to be used in -e or -M):
arm_spe_0// [Kernel PMU event]
Assign capabilities to perf by running:
sudo setcap cap_perfmon,cap_sys_ptrace,cap_sys_admin+ep $(which perf)
If arm_spe isn’t available due to your system configuration or limited PMU access, the perf c2c command will fail.
To confirm perf can access SPE, run:
perf c2c record
If SPE access is blocked, you’ll see output like this:
failed: memory events not supported
If you are unable to use SPE it might be a restriction based on your cloud instance size or operating system.
Generally, access to a full server (also known as metal instances) with a relatively new kernel is required for Arm SPE support.
For more information about enabling SPE, see the perf-arm-spe manual page
You’ve confirmed that your system supports Arm SPE, installed the necessary tools, and verified that Perf C2C can access SPE events. You’re now ready to start collecting detailed performance data using Perf C2C. In the next section, you’ll run a real application and use Perf C2C to capture cache sharing behavior and uncover memory performance issues.