How to run perf in a colima container

2 min read

Just to note down that it’s not straightforward to get perf working.

Here’s what worked finally:

First, the container needs to be started with proper capabilities:

docker run --rm -it --platform linux/amd64 --cap-add PERFMON ubuntu:jammy bash

Secondly, some flags need to be set from the VM:

# this would start a shell in the VM, outside of containers
colima ssh
 
# don't know why, sudo doesn't work, but it works in a root shell
# -1 or 2 both work
sudo bash -c 'echo -1 > /proc/sys/kernel/perf_event_paranoid'

Lastly, install perf in the container:

apt install -y linux-tools-$(uname -r) linux-cloud-tools-$(uname -r)

Then the following works:

perf record -g echo 1
perf report -g graph,0.5,caller

Note also that you can’t pass "echo 1" because perf will failed to find a file named “echo 1”.

Learned this while working on uts-016K and before submitting this issue about unable to run poop in colima containers.

Follow-up:

It’s important to check whether certain perf counters actually work:

sleep 10 &
perf stat -p $! -e "cpu-cycles,instructions,cache-references,cache-misses,branch-misses"

On a machine that supports corresponding counters, it should give something like:

 Performance counter stats for process id '101011':

            511488      cpu-cycles                                                  
            280194      instructions              #    0.55  insn per cycle         
             16193      cache-references                                            
              6161      cache-misses              #   38.047 % of all cache refs    
              8730      branch-misses                                               

      10.009515156 seconds time elapsed

On an unsupported machine, the output would be like:

 Performance counter stats for process id '552':

   <not supported>      cpu-cycles
   <not supported>      instructions
   <not supported>      cache-references
   <not supported>      cache-misses
   <not supported>      branch-misses

       6.491105847 seconds time elapsed

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