leaky-bucket-meter · shipping · also Leaky bucket, Leaky bucket as a meter

Leaky-bucket meter

A leaky-bucket meter tracks work as a level that rises with charges and drains at a configured rate to assess conformance.

Mechanism: work increases the level while elapsed time reduces it toward zero. This is the meter interpretation of a leaky bucket, not a promise of uniformly spaced completions. QEMU v9.2.0 uses this accounting to delay disk I/O and supports bursts. [2] [1]

Accounting: with QEMU iops-size set to 4096 bytes, a 6144-byte request costs 1.5 operations; requests of at most 4096 bytes cost one unit. Drives in one throttle group share limits on their combined I/O. [2] [1]

Relations

related

Token bucket, IOPS, I/O request size, Queue depth

Limitations

• A limiter's charging and waiting rules must be distinguished from the storage device's completion behavior. [2]

Citations

1. QEMU v9.2.0: disk-I/O throttling, operation charging and throttle groups (accessed 2026-11-12)
2. QEMU v9.2.0: throttle_leak_bucket, throttle_compute_wait and throttle_account (accessed 2026-11-12)

Further reading

3. Hesela: rate limits, burst budgets and shared SSD queues (accessed 2026-11-12)

JSON: /data/terms/leaky-bucket-meter.json