Tail Latency Debugger

1. Clone this repository

• git clone git@github.com:inhocho89/llvm14-ldb.git

2. Compile LLVM

• llvm14-ldb> mkdir build
• llvm14-ldb> cd build
• llvm14-ldb/build> cmake -DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_TARGET_ARCH=X86 -DCMAKE_BUILD_TYPE="Release" -DLLVM_BUILD_EXAMPLES=1 -DLLVM_INCLUDE_EXAMPLES=1 -DLLVM_ENABLE_PROJECTS="clang" -G "Unix Makefiles" ../llvm
• llvm14-ldb/build> cmake --build . -j

3. Compile LDB library

• llvm14-ldb/build> cd ../libldb
• llvm14-ldb/libldb> make

1. Compile sample application

• llvm14-ldb> cd apps/demo
• llvm14-ldb/apps/demo> make

2. (optional) run perf to get Linux scheduling data (in a separate terminal)

• llvm14-ldb/apps/demo> sudo perf sched record -k CLOCK_MONOTONIC_RAW

3. Run application with preloading LDB shim layer.

• llvm14-ldb/apps/demo> LD_PRELOAD=/path/to/llvm14-ldb/libldb/libshim.so ./demo

4. When enough data is collected (when the application exits), stop the perf

The raw data is in ldb.data (by LDB) and perf.data (by perf).

1. Parsing latency distribution for each function (this will only use LDB data)

• llvm14-ldb/apps/demo> python3 ../../scripts/parse_summary.py demo > summary

2. Parsing timeline of a request

• llvm14-ldb/apps/demo> python3 ../../scripts/parse_req.py demo 100 > req100