Linux I/O tracing / performance analysis

bt.sh

#! /usr/bin/env bash

# Check if a device argument is provided
if [ "$#" -ne 1 ]; then
    echo "Usage: $0 /dev/<device>"
    exit 1
fi

# Assign the first argument to DEVICE variable
DEVICE=$1

# Start blktrace to monitor block I/O for the specified device for 300 seconds
echo "Starting blktrace on ${DEVICE} for 300 seconds..."
sudo blktrace -w 300 "$DEVICE"

# Extract the device name from the full path (e.g., nvme0n1 from /dev/nvme0n1)
DEV_NAME=$(basename "$DEVICE")

# Process the blktrace binary output with blkparse
echo "Processing blktrace output with blkparse..."
blkparse -d "${DEV_NAME}.bin" -i "$DEV_NAME" -o

# btt is a block trace analysis tool
# -i specifies the blktrace binary input file
# -B specifies the output file for block offsets
echo "Analyzing block trace with btt..."
btt -i "${DEV_NAME}.bin" -B blk_offsets

# Run a custom Python script to further analyze the block offsets
# The filenames for analysis must be adjusted based on actual output files
echo "Running custom analysis with bt_analyze.py..."
./bt_analyze.py "b1k_offsets_259,4_r.dat" "blk_offsets_259,4_w.dat"

echo "Analysis complete."

bt_analyze.py

with open(tracefile) as f:
    for line in f:
        start, end = line.split()[1:]
        start = int(start)
        end = int(end)
        num_ios += 1
        # keep track of sequential segments
        if start != prev_segment:
            num_segments += 1
            prev_segment = end
        # convert sectors to bytes
        SZ = (end - start) / 2
        iosize[SZ] += 1
        total_size += SZ