poll_latency.sh

#!/usr/bin/env bash

# traces a binary for 5s, writing out histograms of the latency of every `Futures::poll` fn

export BINARY_PATH="/home/ubuntu/projects/mini-redis/target/debug/mini-redis-server"

# generate `poll_latency.bpf`

echo "interval:s:5 {
    print(@latency);
    exit();
}" >poll_latency.bpf

objdump -wtT $BINARY_PATH | tr -s ' ' | cut -d' ' -f1,5- | grep 'Future$GT$4poll' \
    | while IFS=" " read -r addr name
      do
        echo "
        uprobe:${BINARY_PATH}:\"${name}\" {
            @start[\"${addr}\"] = nsecs;
        }
        uretprobe:${BINARY_PATH}:\"${name}\" {
            @latency[\"${addr}\"] = hist(nsecs - @start[\"${addr}\"])
        }
        "
      done >> poll_latency.bpf

# run poll_latency.bpf
# notable dependency: rustfilt
sudo bpftrace poll_latency.bpf \
    | awk 'FNR==NR { array[$1]=$2; next } { for (i in array) gsub(i, array[i]) }1' <(objdump -wtT ${BINARY_PATH} | tr -s ' ' | cut -d' ' -f1,5- | grep 'Future$GT$4poll') - \
    | rustfilt \
    | grep -v '@start' \
    | tee histograms