Document ncli_db validatorPerf (#2638)

* add work done so far on ncli_db

* remove file

* Monitor attestation performance: tidy up

* remove test.csv

* tersec's feedback

docs/the_nimbus_book/src/SUMMARY.md

@@ -23,6 +23,7 @@
 - [Recover / generate keys](./more-keys.md)
 - [Perform a voluntary exit](./voluntary-exit.md)
 - [Add an additional validator](./additional-validator.md)
+- [Monitor attestation performance](./attestation-performance.md)
 
 
 # How-to (misc)

docs/the_nimbus_book/src/attestation-performance.md

@@ -0,0 +1,102 @@
+# Monitor attestation performance
+
+Use the `ncli_db validatorPerf` command to create a report for the attestation performance of your validator over time.
+
+## Steps
+
+Make sure you're in the `nimbus-eth2` repository.
+
+### 1. Build ncli_db
+The first step is to build `ncli_db`:
+```
+make ncli_db
+```
+
+### 2. View options
+
+To view the options available to you, run:
+```
+build/ncli_db --help
+```
+
+At the top you should see
+
+```
+ncli_db [OPTIONS]... command
+
+The following options are available:
+
+ --db           Directory where `nbc.sqlite` is stored.
+ --network      The Eth2 network preset to use.
+```
+
+Where:
+
+- The `network` can either be `mainnet`  or `prater`
+
+- The default location of the `db`  is either `build/data/shared_mainnet_0/db` or `build/data/shared_prater_0/db`
+
+
+Near the bottom, you should see
+
+```
+ncli_db validatorPerf [OPTIONS]...
+
+The following options are available:
+
+ --start-slot   Starting slot, negative = backwards from head [=-128 * SLOTS_PER_EPOCH.int64].
+ --slots        Number of slots to run benchmark for, 0 = all the way to head [=0].
+```
+
+Use `start-slot` and `slots` to restrict the analysis on a specific block range.
+
+### 3. Run
+
+To view the performance of all validators on Prater so far across the entire block range stored in your database, run:
+```
+build/ncli_db validatorPerf \
+--network=prater \
+--db=build/data/shared_prater_0/db
+```
+
+You should see output that looks like to the following:
+
+```
+validator_index,attestation_hits,attestation_misses,head_attestation_hits,head_attestation_misses,target_attestation_hits,target_attestation_misses,delay_avg,first_slot_head_attester_when_first_slot_empty,first_slot_head_attester_when_first_slot_not_empty
+0,128,0,127,1,128,0,1.0078125,0,3
+1,128,0,125,3,127,1,1.0078125,0,2
+2,128,0,127,1,127,1,1.0078125,0,5
+...
+```
+
+### 4. Adjust to target a specific block range
+
+To restrict the analysis to the performance between slots 0 and 128, say, run:
+```
+build/ncli_db validatorPerf \
+--network=prater \
+--db=build/data/shared_prater_0/db \
+--start-slot=0 \
+--slots=128
+```
+
+### 5. Compare my validators to the global average
+
+We'll use [Paul Hauner's wonderful workbook](https://docs.google.com/spreadsheets/d/1SNFf4LsDOK91SWuQZm9DYBoX9JNQNMKHw66Rv0l5EGo/) as a template. This workbook consists of three inter-related spreadsheets - `Summary`, `My Validators`, and `datasource`.
+
+1. Make a copy of the document
+
+2. Remove the table entries in `My Validators` and delete everything in the `datasource` sheet
+
+3. Import the output from `validatorPerf` to `datasource` - the easiest way to do this is to pipe the output to a `csv`, remove the first few lines, and import the `csv` into `datasource`
+
+4. Manually copy over your validator(s) to the `My Validators` sheet  - the easiest way to find your validator's  `validator_index` is to search for it by its public key on [beaconcha.in](https://beaconcha.in/) (for example, [this validator's](https://beaconcha.in/validator/115733) index is 115733)
+
+5. Go to the `Summary` page and view your results
+
+
+## Resources
+
+The workbook's method  is explained [here](https://hackmd.io/xQfi83kHQpm05-aAFVV0DA?view).
+
+