From 3e1246984cd25b917e94f73902a2da480570d6dc Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Mon, 19 Jan 2026 19:26:30 +0000
Subject: [PATCH] Adjust pool defaults for many core systems with undetected
 topologies.

Signed-off-by: Jason Volk <jason@zemos.net>
---
 docker/Dockerfile.cargo        |  2 ++
 docker/bake.hcl                | 11 ++++++++++-
 src/core/config/mod.rs         |  3 +--
 src/database/pool/configure.rs |  3 ++-
 tuwunel-example.toml           |  3 +--
 5 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/docker/Dockerfile.cargo b/docker/Dockerfile.cargo
index abffaa72..455f98d5 100644
--- a/docker/Dockerfile.cargo
+++ b/docker/Dockerfile.cargo
@@ -18,6 +18,7 @@ ARG RUST_BACKTRACE
 ARG JEMALLOC_OVERRIDE
 ARG ROCKSDB_LIB_DIR
 ARG VALGRINDFLAGS=""
+ARG VALGRIND_MAX_WORKERS=128
 ARG CARGO_BUILD_RUSTFLAGS
 ARG CARGO_PROFILE_TEST_DEBUG
 ARG CARGO_PROFILE_TEST_INCREMENTAL
@@ -53,6 +54,7 @@ ENV RUST_BACKTRACE="${RUST_BACKTRACE}"
 ENV JEMALLOC_OVERRIDE="${JEMALLOC_OVERRIDE}"
 ENV ROCKSDB_LIB_DIR="${ROCKSDB_LIB_DIR}"
 ENV VALGRINDFLAGS="${VALGRINDFLAGS}"
+ENV TUWUNEL_DB_POOL_MAX_WORKERS="${VALGRIND_MAX_WORKERS}"
 ENV CARGO_PROFILE_TEST_DEBUG="${CARGO_PROFILE_TEST_DEBUG}"
 ENV CARGO_PROFILE_TEST_INCREMENTAL="${CARGO_PROFILE_TEST_INCREMENTAL}"
 ENV CARGO_PROFILE_BENCH_DEBUG="${CARGO_PROFILE_BENCH_DEBUG}"
diff --git a/docker/bake.hcl b/docker/bake.hcl
index cacb55fe..55476414 100644
--- a/docker/bake.hcl
+++ b/docker/bake.hcl
@@ -450,10 +450,18 @@ group "integration" {
     ]
 }
 
+variable "valgrind_max_workers" {
+    default = 128
+}
+
 variable "valgrind_flags" {
     default = "--error-exitcode=1 --exit-on-first-error=yes --undef-value-errors=no --leak-check=no"
 }
 
+variable "valgrind_testee_args" {
+    default = "-Odb_pool_max_workers=${valgrind_max_workers}"
+}
+
 target "rust-sdk-valgrind" {
     name = elem("rust-sdk-valgrind", [cargo_profile, rust_toolchain, rust_target, feat_set, sys_name, sys_version, sys_target])
     tags = [
@@ -469,7 +477,7 @@ target "rust-sdk-valgrind" {
     }
     args = {
         VALGRINDFLAGS = "${valgrind_flags}"
-        mrsdk_testee = "valgrind ${valgrind_flags} /usr/bin/tuwunel"
+        mrsdk_testee = "valgrind ${valgrind_flags} /usr/bin/tuwunel ${valgrind_testee_args}"
         mrsdk_test_args = ""
         mrsdk_startup_delay = "30s"
         mrsdk_skip_list =<<EOF
@@ -522,6 +530,7 @@ target "integ-valgrind" {
         input = elem("target:build-tests", [cargo_profile, rust_toolchain, rust_target, feat_set, sys_name, sys_version, sys_target])
     }
     args = {
+        VALGRIND_MAX_WORKERS = "${valgrind_max_workers}"
         VALGRINDFLAGS = "${valgrind_flags}"
         cargo_cmd = "valgrind test"
         cargo_args = "--test=*"
diff --git a/src/core/config/mod.rs b/src/core/config/mod.rs
index 9190dd7c..ed1f5e75 100644
--- a/src/core/config/mod.rs
+++ b/src/core/config/mod.rs
@@ -1987,8 +1987,7 @@ pub struct Config {
 	/// Sets the number of worker threads in the frontend-pool of the database.
 	/// This number should reflect the I/O capabilities of the system,
 	/// such as the queue-depth or the number of simultaneous requests in
-	/// flight. Defaults to 32 or four times the number of CPU cores, whichever
-	/// is greater.
+	/// flight. Defaults to 32 times the number of CPU cores.
 	///
 	/// Note: This value is only used if db_pool_affinity is disabled or not
 	/// detected on the system, otherwise it is determined automatically.
diff --git a/src/database/pool/configure.rs b/src/database/pool/configure.rs
index 3a60b154..b47f618b 100644
--- a/src/database/pool/configure.rs
+++ b/src/database/pool/configure.rs
@@ -69,7 +69,8 @@ pub(super) fn configure(server: &Arc<Server>) -> (Vec<usize>, Vec<usize>, Vec<us
 	// The default worker count is masked-on if we didn't find better information.
 	let default_worker_count = topology_detected
 		.is_false()
-		.then_some(config.db_pool_workers);
+		.then_some(config.db_pool_workers)
+		.map(|workers| workers.saturating_mul(num_cores));
 
 	// Sum the total number of possible tags. When no hardware detected this will
 	// default to the default_worker_count. Note well that the thread-worker model
diff --git a/tuwunel-example.toml b/tuwunel-example.toml
index 4f67eb05..66adcbe1 100644
--- a/tuwunel-example.toml
+++ b/tuwunel-example.toml
@@ -1712,8 +1712,7 @@
 # Sets the number of worker threads in the frontend-pool of the database.
 # This number should reflect the I/O capabilities of the system,
 # such as the queue-depth or the number of simultaneous requests in
-# flight. Defaults to 32 or four times the number of CPU cores, whichever
-# is greater.
+# flight. Defaults to 32 times the number of CPU cores.
 #
 # Note: This value is only used if db_pool_affinity is disabled or not
 # detected on the system, otherwise it is determined automatically.