OSM Dirty Memory
Linux dirty memory limits during OSM load.
Each point is a host-local OSM load on siren (PostgreSQL 17, 128GB RAM, fast SSD) at a different Linux dirty-memory cap. Throughput stays near 700 kNodes/s from the default ~13.4GB dirty cache down to a 95MB byte limit—only a mild drop below 1GB. On this SSD, a large Dirty cache is not buying much; a few GB is enough to keep the drive fed.
Regenerate: python3 reports/osm-dirty-memory.py (reads docs/results-summary/pg18/osm-dirty-memory.md).
Snapshot of the Streamlit explorer — down between releases (OSM Dirty Memory) on 2026-08-09. Captured by explorer/snapshot-streamlit.py from the live site.
Query returned 9 rows.
| batch | hours | nodes | nodes_kips | index_kips | max_dirty | wal_mbps | avg_write_mbps | max_write_mbps |
|---|---|---|---|---|---|---|---|---|
| sk41 disk | 3.16 | 8039181739.0 | 706.0 | 298.0 | 12659957760 | 19.5 | 113.0 | 3626.0 |
| sk41 disk | 3.15 | 8039181739.0 | 709.0 | 309.0 | 14284529664 | 19.6 | 115.0 | 3955.0 |
| sk41 disk | 3.14 | 8039181739.0 | 710.0 | 310.0 | 14405595136 | 19.6 | 115.0 | 2516.0 |
| Dirty ratios 5/10 | 3.19 | 8039181739.0 | 700.0 | 306.0 | 7828504576 | 19.3 | 114.0 | 3312.0 |
| Dirty ratios 1/2 | 3.16 | 8039181739.0 | 707.0 | 306.0 | 1414533120 | 19.5 | 115.0 | 3287.0 |
| Dirty ratios 2/4 | 3.16 | 8039181739.0 | 707.0 | 304.0 | 2750353408 | 19.5 | 115.0 | 3654.0 |
| Dirty bytes 1000MB/500MB | 3.2 | 8039181739.0 | 699.0 | 295.0 | 992743424 | 19.3 | 114.0 | 3595.0 |
| Dirty bytes 500MB/250M | 3.17 | 8039181739.0 | 705.0 | 300.0 | 481751040 | 19.5 | 113.0 | 3387.0 |
| Dirty bytes 100MB/50MB | 3.2 | 8039181739.0 | 699.0 | 294.0 | 99667968 | 19.3 | 114.0 | 2288.0 |