build: DTail fork — benchmarks, PGO tooling, Makefile, docker

Squashed development of the build/benchmark/profiling tooling:

- Turbo-vs-normal and per-tool benchmark harnesses under benchmarks/ (with dated
  baseline and result artifacts preserved), plus MapReduce/SSH/network suites.
- Profile-Guided Optimization workflow (internal/tools/pgo lives with the code):
  Makefile targets (make pgo / pgo-quick / build-pgo), profile generation with
  non-zero-sample and representativeness guards.
- Makefile targets for build, test (unit + integration), lint, vet, benchmarking
  and profiling; docker config updates.
- .gitignore hardened against pgo profiles and accidental integration-test
  debug/output dumps.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 75 insertions, 0 deletions

diff --git a/benchmarks/baselines/benchmark_comparison_report.md b/benchmarks/baselines/benchmark_comparison_report.md
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+# Benchmark Comparison Report: v4.3.0 vs Turbo-Enabled
+
+## Summary
+
+This report compares the performance of DTail v4.3.0 (baseline) with the current version that has turbo boost mode enabled by default.
+
+## Performance Improvements
+
+### DCat Operations
+- **10MB file**: 
+  - v4.3.0: 9.363 MB/sec
+  - Turbo: 246.8 MB/sec
+  - **Improvement: 2,535% (26.3x faster)**
+
+### DGrep Operations (10MB file)
+- **1% hit rate**:
+  - v4.3.0: 25.38 MB/sec
+  - Turbo: 363.9 MB/sec
+  - **Improvement: 1,334% (14.3x faster)**
+
+- **10% hit rate**:
+  - v4.3.0: 22.81 MB/sec
+  - Turbo: 342.6 MB/sec
+  - **Improvement: 1,402% (15.0x faster)**
+
+- **50% hit rate**:
+  - v4.3.0: 16.14 MB/sec
+  - Turbo: 265.1 MB/sec
+  - **Improvement: 1,543% (16.4x faster)**
+
+- **90% hit rate**:
+  - v4.3.0: 10.99 MB/sec
+  - Turbo: 210.0 MB/sec
+  - **Improvement: 1,811% (19.1x faster)**
+
+### DMap Operations (10MB file)
+- **Count query**:
+  - v4.3.0: 17.09 MB/sec
+  - Turbo: 21.77 MB/sec
+  - **Improvement: 27.4%**
+
+- **Sum/Avg query**:
+  - v4.3.0: 13.54 MB/sec
+  - Turbo: 21.05 MB/sec
+  - **Improvement: 55.5%**
+
+- **Min/Max query**:
+  - v4.3.0: 17.46 MB/sec
+  - Turbo: 21.80 MB/sec
+  - **Improvement: 24.9%**
+
+- **Multi-field query**:
+  - v4.3.0: 21.85 MB/sec
+  - Turbo: 21.32 MB/sec
+  - **Slight decrease: -2.4%** (within margin of error)
+
+## Key Findings
+
+1. **Massive improvements in DCat and DGrep**: The turbo boost mode shows extraordinary performance gains for file reading (DCat) and searching (DGrep) operations, with improvements ranging from 14x to 26x faster.
+
+2. **Moderate improvements in DMap**: MapReduce operations show more modest but still significant improvements of 25-55% for most query types.
+
+3. **Consistent performance across hit rates**: DGrep performance improvements scale well across different hit rates, with even better improvements at higher hit rates.
+
+## Technical Details
+
+The turbo boost mode achieves these improvements through:
+- Direct writing bypassing channels for cat/grep/tail operations
+- Direct line processing without channels for MapReduce in server mode
+- Batch processing to reduce lock contention
+- Memory pooling to reduce garbage collection pressure
+
+## Recommendation
+
+The turbo boost mode delivers exceptional performance improvements and should remain enabled by default. The performance gains are substantial enough to justify any potential trade-offs in code complexity.
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