In this case CPU event refers to monitoring events per CPU rather than per task. For perf tools this restricts the usage of -C, –cpu= Count only on the list of CPUs provided. Multiple CPUs can be provided as a comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2. In … Read more
Alright, well, let’s ignore temporarily the difference between caller and callee call-graphs, mostly because when I compare the results between these two options on my machine, I only see effects inside the kernel.kallsyms DSO for reasons I don’t understand — relatively new to this myself. I found that for your example, it’s a little easier … Read more
Make sure you compiled the code with -fno-omit-frame-pointer gcc option.
What is your kernel? Is it from the linux distributive you use or is it compiled by you (how did you install it)? First part of warning says about /proc/kallsyms – can you show output of the command (started from the same user you used to run perf) ls -l /proc/kallsyms cat /proc/kallsyms | head … Read more
As of 2018, perf simply doesn’t have support for reading the Python stack frames (cf. a 2014 Python mailinglist discussion). Python 3.6 has some support for Dtrace and Systemtap. An alternative to this is Pyflame, a stochastic profiler for Python that samples python call stacks via ptrace(). In contrast to Dtrace/Systemtap you don’t need extra … Read more
Some answers: L1 is the Level-1 cache, the smallest and fastest one. LLC on the other hand refers to the last level of the cache hierarchy, thus denoting the largest but slowest cache. i vs. d distinguishes instruction cache from data cache. Only L1 is split in this way, other caches are shared between data … Read more
This post is already over a year old, but since it came out at the top of my Google search results when I had the same problem, I thought I’d answer it here. After some more searching around, I found the answer given in this related StackOverflow question very helpful. On my Ubuntu Raring system, … Read more
WARNING: perf not found for kernel 4.19.84-microsoft Because WSL2 uses custom Linux kernel. Its source code can be found here microsoft/WSL2-Linux-Kernel. We have to compile perf tools from it. Procedure Install required build packages. If you are using Ubuntu in WSL2 this is the required command: sudo apt install build-essential flex bison libssl-dev libelf-dev Clone … Read more
On my system, an Intel Xeon X5570 @ 2.93 GHz I was able to get perf stat to report cache references and misses by requesting those events explicitly like this perf stat -B -e cache-references,cache-misses,cycles,instructions,branches,faults,migrations sleep 5 Performance counter stats for ‘sleep 5’: 10573 cache-references 1949 cache-misses # 18.434 % of all cache refs 1077328 … Read more
1) By default, perf stat shows task-clock, and does not show cpu-clock. Therefore we can tell task-clock was expected to be much more useful. 2) cpu-clock was simply broken, and has not been fixed for many years. It is best to ignore it. It was intended that cpu-clock of sleep 1 would show about 1 … Read more