Performance & Tracing Update

High level summary

• Benchmarking: Van Rossem HF: Created and performed benchmarks for new Plutus execution budgets and internals; PlutusV3 baseline shift.
• Development: Hermod package restructre completed; cardano-config support in trace-dispatcher.
• Infrastructure: Genesis cache overhaul / Protocol Version 11 overlay have landed.
• Tracing: Alert manager feature for cardano-tracer in design phase; native support for spans in Hermod.
• Leios: Major new beacon feature to impose memory limits; on-disk LedgerDB tx validation times benchmark in the works.

Low level overview

Benchmarking

The P&T team has been safeguarding the now enacted Van Rossem hard fork, which brings Protocol Version 11 with new Plutus internals and a bump to the execution budgets to mainnet. Our benchmarking automation framework, the performance workbench, gained new chain-fragment-creation profiles as well as new plutuscall-* profiles, targeting those new Plutus features specifically (cardano-node PR#6627 and cardano-node PR#6440). The former PR also adds a wb chain-fragment export op, which packages a profile run's node database, genesis files and a path-patched node config into a chain fragment consumable by beacon tool — the tooling behind the on-disk benchmarks described under Leios below.

The benchmarks performed using those new profiles have shown that the execution budget raise leads to a reasonable, predictable and expected increase in Block Adoption times. For the new PlutusV3 internals, they've also shown that they're consistently priced relative to the existing internals, and that, even when executed up to full budget exhaustion, there were no performance regressions in their implementation.

To enable those benchmarks, work has been well underway on extending plutus-scripts-bench with PlutusV3 variants of the existing scripts, and adding two new PV11 scripts targeting the new execution internals: MultiScalarMulG1 (BLS12-381 multi-scalar multiplication based on CIP-0133), and ExpModInteger, exercising the new expModInteger builtin (cardano-node PR#6440). The PR wires these through to tx-generator, and gives our analysis tool locli a new PlutusBudgetSummary module to output Plutus workload calibration data as part of comparison reports. The PR is currently under review.

Development

The long-planned restructuring of trace-dispatcher into separate Hermod packages, which we reported as underway last month, is now complete (hermod-tracing PR#16). The stable API surface — trace types, LogFormatting/MetaTrace instances, and the structural/annotation combinators — now lives in a lightweight hermod-tracing-api package, itself split into an internal and a public sublibrary, so that packages which only need to instrument their own code no longer pull in EKG, Prometheus, CBOR forwarding or the YAML config parser as dependencies. The full backend stack remains in hermod-tracing-core, while the Prometheus TCP server has been carved out into its own optional hermod-tracing-prometheus package. All modules and identifiers were renamed from Cardano.Logging.*/TraceDispatcherMessage and friends to their Hermod.Tracing.* equivalents, and trace-dispatcher itself has been kept around as a backward-compatible mirror so existing pinned consumers keep building unchanged until they migrate.

Last but not least, we've added compatibility with the cardano-config library to trace-dispatcher (hermod-tracing PR#18).

Infrastructure

The genesis cache overhaul and full Protocol Version 11 overlay for our performance workbench, close to merging as of last month, have now landed (cardano-node PR#6544). Beyond the split-cache "ripper" backend and the restoration of non-default Plutus cost models via the Alonzo genesis extraConfig field reported previously, the merged PR also standardises genesis creation on cardano-cli's create-testnet-data (retiring the old create-staked path and the separate byron genesis step), makes the era an explicit, validated input to wb start and wb run allocate via a new --era-name flag, and simplifies the workbench CLI to named flags only. A handful of breaking changes ship alongside: WB_BACKEND is renamed to WB_BACKEND_NAME, --relays and the genesis "spec" sub-command are removed, and non-default Plutus cost models must now be supplied through extraConfig. Analysis of older runs is unaffected, as wb analyse falls back to the previous genesis layout when the new one is absent.

Tracing

We've begun designing a central alarm system for cardano-tracer (alarm system concept). Today, operators typically rely on third-party tooling for this — something built on top of Grafana, the Prometheus Alertmanager, or Loki log analysis — but there's no solution native to the tracing and metrics stack, and none that takes a unified approach across trace messages and metrics. The idea is to instead give cardano-tracer a single place that collects alarms from multiple sources — our hermod-recon verifier flagging a violated property, a rule evaluated against the metrics cardano-tracer already stores, or simply a trace message severe enough to warrant attention — and forward them to wherever operators want to be notified — typically a paging service's webhook API, but custom webhooks, email, and plain logging are supported too — while keeping a queryable history of past alarms. It deliberately stays a one-shot notification layer rather than a full incident tracker: there's no acknowledgement or resolution workflow, that's left to whatever tooling operators already use for that. This is still an early design and not yet reflected in any implementation work.

On the Hermod side, we're also exploring native support for nested spans, in the spirit of tracing systems like OpenTelemetry. A span represents a bounded unit of work — say, processing a single transaction or forging a block — and the point is to let automated log analysis reconstruct not just individual events, but how long an operation took and how it decomposes into sub-operations, by pairing up an opening and a closing trace message that share a unique identifier. The tricky part is Haskell's laziness: without care, an expression's evaluation, and the trace events it triggers, can end up happening after its enclosing span has already been closed, so a fair amount of the design work goes into guaranteeing that no trace event ever escapes the span it logically belongs to. There's no branch to point to yet — this is still exploratory work.

Leios

Building on the chain-fragment export tooling introduced above, beacon — the ledger ops benchmarking tool in ouroboros-consensus-tools — gained a memory-limiting feature aimed squarely at tx validation times using an on-disk LedgerDB backend and forcing disk I/O at the same time (beacon PR#12, currently under review).

A new flag forces the LSM (on-disk) backend to genuinely exercise disk I/O, rather than being served invisibly out of the OS page cache; --mem-limit/--heap-limit cgroup caps serve as a fallback for past db-analyser builds without support for that new flag. Every run now records peak RSS and block I/O counts. A representative "sweet spot" using those new mechanisms has been determined empirically for the chain fragments used in this year's April measurements. This finally gives us concrete on-disk LedgerDB metrics by determining the overhead of I/O-backed validation times vs. pure ones, closing a gap in our Leios throughput benchmarking. A new beacon/docs/METHODOLOGY.md documents the overall approach; benchmarks are currently being performed on our benchmarking cluster, to obtain measurements on the same hardware as we did in April for the in-memory backend — but now with LSM backend forced to perform disk I/O.