From 9db57a85c05e08ddc4c48dd31c16ef7ae2b7febe Mon Sep 17 00:00:00 2001
From: Filip Skokan <panva.ip@gmail.com>
Date: Sun, 6 Sep 2026 17:51:43 +0200
Subject: [PATCH 1/2] tools: improve benchmark build cache reuse

Match Linux x64 benchmark builds to the Perfetto-enabled V8
configuration already cached by shared-library CI.

Enable the GHA sccache backend in read-only mode for base builds.
Retain the compiler wrapper for incremental PR builds, but stop the
remote-backed server and use a read-only local cache for PR code.

Assisted-by: GitHub Copilot
Signed-off-by: Filip Skokan <panva.ip@gmail.com>
---
 .github/workflows/benchmark.yml | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/benchmark.yml b/.github/workflows/benchmark.yml
index b512153621d8..9b15d5d4ecae 100644
--- a/.github/workflows/benchmark.yml
+++ b/.github/workflows/benchmark.yml
@@ -69,13 +69,14 @@ jobs:
         include:
           - runner: ubuntu-24.04
             system: x86_64-linux
+            perfetto: true
           - runner: ubuntu-24.04-arm
             system: aarch64-linux
           - runner: macos-15-intel
             system: x86_64-darwin
           - runner: macos-latest
             system: aarch64-darwin
-    name: '${{ matrix.system }}: with shared libraries'
+    name: '${{ matrix.system }}: with shared libraries${{ matrix.perfetto && '' and perfetto'' || '''' }}'
     runs-on: ${{ matrix.runner }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
@@ -105,24 +106,30 @@ jobs:
         uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3  # v9.0.0
         with:
           script: |
-            core.exportVariable('SCCACHE_GHA_VERSION', 'on');
+            core.exportVariable('SCCACHE_GHA_ENABLED', 'on');
+            core.exportVariable('SCCACHE_GHA_RW_MODE', 'READ_ONLY');
             core.exportVariable('ACTIONS_CACHE_SERVICE_V2', 'on');
             core.exportVariable('ACTIONS_RESULTS_URL', process.env.ACTIONS_RESULTS_URL || '');
             core.exportVariable('ACTIONS_RUNTIME_TOKEN', process.env.ACTIONS_RUNTIME_TOKEN || '');
+            core.exportVariable('NIX_SCCACHE', '(import <nixpkgs> {}).sccache');
 
       - name: Build Node.js on the base commit
         run: |
           nix-shell \
             -I nixpkgs=./tools/nix/pkgs.nix \
             --pure --keep TAR_DIR --keep FLAKY_TESTS \
-            --keep SCCACHE_GHA_ENABLED --keep ACTIONS_CACHE_SERVICE_V2 --keep ACTIONS_RESULTS_URL --keep ACTIONS_RUNTIME_TOKEN \
+            --keep SCCACHE_GHA_ENABLED --keep SCCACHE_GHA_RW_MODE \
+            --keep ACTIONS_CACHE_SERVICE_V2 --keep ACTIONS_RESULTS_URL --keep ACTIONS_RUNTIME_TOKEN \
             --arg useSeparateDerivationForV8 true \
+            --arg withPerfetto ${{ matrix.perfetto || false }} \
             --arg loadJSBuiltinsDynamically false \
             --arg ccache "${NIX_SCCACHE:-null}" \
             --arg devTools '[]' \
             --arg benchmarkTools '[]' \
             --run '
+                set -e
                 make build-ci -j4 V=1
+                sccache --stop-server
             '
           mv out/Release/node base_node
 
@@ -130,19 +137,22 @@ jobs:
         run: git reset FETCH_HEAD --hard
 
       - name: Re-build Node.js on the merge commit
-        # ccache is disabled here to avoid polluting the cache. Local build outputs should make this build relatively quick anyway.
+        # Keep the compiler command unchanged for incremental builds, but never cache PR build outputs.
         run: |
           nix-shell \
             -I nixpkgs=./tools/nix/pkgs.nix \
-            --pure \
+            --pure --keep SCCACHE_LOCAL_RW_MODE \
             --arg useSeparateDerivationForV8 true \
+            --arg withPerfetto ${{ matrix.perfetto || false }} \
             --arg loadJSBuiltinsDynamically false \
-            --arg ccache 'null' \
+            --arg ccache "${NIX_SCCACHE:-null}" \
             --arg devTools '[]' \
             --arg benchmarkTools '[]' \
             --run '
                 make build-ci -j4 V=1
             '
+        env:
+          SCCACHE_LOCAL_RW_MODE: READ_ONLY
 
       - name: Run benchmark
         run: |

From e01854636c7bcfce379910229d1ecc61dbcd4b01 Mon Sep 17 00:00:00 2001
From: Filip Skokan <panva.ip@gmail.com>
Date: Sun, 6 Sep 2026 22:51:58 +0200
Subject: [PATCH 2/2] fixup! tools: improve benchmark build cache reuse

---
 .github/workflows/benchmark.yml | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/benchmark.yml b/.github/workflows/benchmark.yml
index 9b15d5d4ecae..924feb42725e 100644
--- a/.github/workflows/benchmark.yml
+++ b/.github/workflows/benchmark.yml
@@ -111,7 +111,6 @@ jobs:
             core.exportVariable('ACTIONS_CACHE_SERVICE_V2', 'on');
             core.exportVariable('ACTIONS_RESULTS_URL', process.env.ACTIONS_RESULTS_URL || '');
             core.exportVariable('ACTIONS_RUNTIME_TOKEN', process.env.ACTIONS_RUNTIME_TOKEN || '');
-            core.exportVariable('NIX_SCCACHE', '(import <nixpkgs> {}).sccache');
 
       - name: Build Node.js on the base commit
         run: |
@@ -123,13 +122,11 @@ jobs:
             --arg useSeparateDerivationForV8 true \
             --arg withPerfetto ${{ matrix.perfetto || false }} \
             --arg loadJSBuiltinsDynamically false \
-            --arg ccache "${NIX_SCCACHE:-null}" \
+            --arg ccache '(import <nixpkgs> {}).sccache' \
             --arg devTools '[]' \
             --arg benchmarkTools '[]' \
             --run '
-                set -e
-                make build-ci -j4 V=1
-                sccache --stop-server
+              make build-ci -j4 V=1 && sccache --stop-server
             '
           mv out/Release/node base_node
 
@@ -145,7 +142,7 @@ jobs:
             --arg useSeparateDerivationForV8 true \
             --arg withPerfetto ${{ matrix.perfetto || false }} \
             --arg loadJSBuiltinsDynamically false \
-            --arg ccache "${NIX_SCCACHE:-null}" \
+            --arg ccache '(import <nixpkgs> {}).sccache' \
             --arg devTools '[]' \
             --arg benchmarkTools '[]' \
             --run '