Set default database threads to 13

Author: joshua-spacetime

crates/standalone/src/subcommands/start.rs

@@ -94,6 +94,7 @@ pub fn cli() -> clap::Command {
         .arg(
             Arg::new("dedicated_database_cores")
                 .long("dedicated-database-cores")
+                .default_value("13")
                 .value_parser(clap::value_parser!(usize))
                 .help(
                     "Pin exactly this many database executors to dedicated cores. On Linux, Tokio, Rayon, and blocking threads are restricted to the remaining cores while the OS schedules them within that set.",

tools/tpcc-runner/README.md

@@ -58,7 +58,9 @@ cargo run --release -p spacetimedb-cli -- start --listen-addr 127.0.0.1:3000
 
 For standalone multi-database runs, it is usually worth setting
 `--dedicated-database-cores` to the number of databases so each database gets
-its own dedicated database executor core. For example, with `12` databases:
+its own dedicated database executor core. The current standalone default is
+`13`, so override it when your database count differs. For example, with `12`
+databases:
 
 ```bash
 cargo run --release -p spacetimedb-cli -- start \