Analysis of block validation times (#471)

* Repeated and expanded `db-analyser` analysis
* Updated logbook

Author: bwbush

Logbook.md

@@ -1,5 +1,28 @@
 # Leios logbook
 
+## 2025-07-24
+
+### Revised analysis of block and transaction validation times
+
+We completed the basic analysis of block and transaction validation times for Cardano `mainnet` since Epoch 350. Results differ significantly from the preliminary results because it was discovered that `db-analyser` output is not reliable when it is run on a machine that has other CPU load: the new analysis is based on a clean dataset that was run on an otherwise idle machine.
+
+Findings:
+
+1. The `db-analyser` tool can be used to measure the Cardno block-application time, either including or not including verifying transaction signatures and running Plutus scripts.
+2. Ideally, `db-analyser` could be modified to report CPU times for phase 1 and phase 2 validation on a per-transaction basis.
+3. The output of this tool is quite noisy and does not include enough of the explanatory variable for predicting CPU times for transactions or blocks.
+4. The missing explanatory variables (size of UTxO set, number of inputs, number of outputs, etc.) can be extracted from the ledger or `cardano-db-sync`.
+5. For transaction signature verification and Plutus script execution, the median times are . . .
+    - 3.675 μs/tx
+    - 1.946 μs/kB
+    - Jointly via a linear model, 7.353 μs/tx plus 1.474 μs/kB.
+    - Jointly via a linear model, 7.271 μs/tx plus 0.938 μs/kB plus 5.463 μs/Gstep, with a Lapace-distributed error having location 0 μs and scale 145 μs.
+6. The noise in the data and the uncertainty in predictions make the above values unsuitable for estimating individual transactions but suitable for bulk estimates of many blocks.
+7. A more sophisticated double general linear model could be used to generate artificial transaction workloads.
+8. The CPU-timing parameters in the default configuration for Leios simulations could be reduced based on this work.
+
+See [the Jupyter notebook](analysis/timings/ReadMe.ipynb) for evidence and details.
+
 ## 2025-07-21
 
 ### Generic analysis script for Leios simulator output

analysis/sims/kernels.nix

@@ -23,6 +23,7 @@
       R_utils
       stringr
       svglite
+      VGAM
     ];
   };
 }