btt
Analyze block layer I/O trace data
TLDR
SYNOPSIS
btt [options] -i tracefile_
DESCRIPTION
btt (Block Trace Timeline) analyzes block layer trace data generated by blktrace. It produces statistical reports showing I/O latency distributions, throughput, and timing breakdowns across the block I/O stack.The analysis breaks down request processing into stages: Q (queued), G (get request), I (inserted), M (merged), D (dispatched), C (completed). btt reports latencies between these stages to identify bottlenecks.Output includes overall statistics, per-device breakdowns, and optional detailed timing files for each stage transition. This data is valuable for understanding storage performance characteristics and diagnosing latency issues.
PARAMETERS
-i file
Input trace file (from blkparse -d).-o prefix
Output file prefix.-q file
Write Q2C latency data.-d file
Write D2C latency data.-l file
Write per-IO latency data.-m file
Write D2D seek distance data.-B file
Write block number data.-v
Verbose output.-V
Version information.-a
Include all accounting.-M
Only display device mapping info.
INSTALL
CAVEATS
Requires binary trace data from blkparse -d, not raw blktrace files. Large traces produce large analysis output. Timestamps must be synchronized for meaningful analysis. Output files can be plotted with gnuplot for visualization.
HISTORY
btt was developed alongside blktrace by Alan D. Brunelle as part of the Linux block layer tracing infrastructure, included in the blktrace package since its introduction in Linux kernel 2.6.17 (2006). It provides the analytical companion to blktrace's data collection capabilities, enabling detailed performance analysis of the block I/O subsystem.
