ZNWorkload

Test workloads for ZNS

Setup

Clone repo:

git clone https://github.com/johnramsden/ZNWorkload.git --recursive

Compile dependencies:

./build-deps.sh

Compile project:

meson setup buildDir
meson compile -C buildDir

There are various variables that can be set: (defaults in meson_options.txt)

• debugging: Enables debug output (default true)
• debugsymbols: Enables debug symbols
• verify: Enables correctness verification (default true)
• BLOCK_ZONE_CAPACITY: Sets SSD zone size (default 1077MiB 1129316352)
• READ_SLEEP_US: Read delay to simulate remote data (default 40430us)
• PROFILING_INTERVAL_SEC: Interval to print metrics on (averaged) (default 10)
• PROFILER_PRINT_EVERY: Print metrics on every call, not just at interval (default true)
• EVICT_HIGH_THRESH_ZONES: High water mark for zone eviction
• EVICT_LOW_THRESH_ZONES: Low water mark for zone eviction
• EVICT_HIGH_THRESH_CHUNKS: High water mark for chunk eviction
• EVICT_LOW_THRESH_CHUNKS: Low water mark for chunk eviction
• EVICT_INTERVAL_US: Sleep time between evictions (us) (default 100,000, or 0.1s)
• EVICTION_POLICY: (ZN_EVICT_PROMOTE_ZONE, ZN_EVICT_CHUNK) Eviction policy, default ZN_EVICT_PROMOTE_ZONE
• MAX_ZONES_USED: Set maximum zones to use (default 0 means all)

To modify these:

meson setup --reconfigure buildDir -Dverify=true -Ddebugging=true -DBLOCK_ZONE_CAPACITY=1048576
meson compile -C buildDir

Scheduler

IMPORTANT: Must use a non re-ordering scheduler such as mq-deadline, set accordingly in /sys/block/$DEVICE/queue/scheduler

echo mq-deadline | tee /sys/block/$DEVICE/queue/scheduler
cat /sys/block/$DEVICE/queue/scheduler

Testing and Development

Create an emulated ZNS device via scripts/nullblk-zones.sh with:

• sector size: 4096B
• zone size: 32MiB
• conventional zones (non seq writes): 0
• sequential zones: 100

./scripts/nullblk.sh 4096 32 0 100 "zns" # or ssd

Created /dev/nullb0

To destroy:

./scripts/nullblk-zoned-delete.sh 0 # Replace 0 with ID if different

Workloads

For detailed experiment reproduction, see WORKLOADS

Min-workload

For mini-test:

• 14 zones
• 8chunks per zone
• 2*14=28 is capacity
• Start evict at 2 zones free: 24 entries
• On evict, evict 4 zones: 20 entries remain

ZNS:

./scripts/nullblk.sh 4096 1 0 14 "zns"

On SSD:

./scripts/nullblk.sh 4096 1 0 14 "ssd"

./zncache /dev/nullb0 524288 2

This means 2chunks to fill a zone: 1024*1024/2

Documentation

Run doxygen:

doxygen Doxyfile

Open docs/html/index.html in a browser.

Formatting

Run clang-format:

clang-format -i src/ze_cache.c