I want to start a discussion about enabling PGO for release builds on Windows. Along with LTO (enabled since v26.3), it will further improve Node.js performance on Windows. While LTO builds took 3-3.5 hours initially, recent changes have reduced them to around 2 hours. Enabling PGO will double that time (2 builds are needed plus running workload scripts in between), but overall it will be a bit longer than what LTO took last week. Additionally, I would only enable PGO for release builds, so nightly and canary builds would be unaffected. I feel confident in enabling this because I've already tested it thoroughly in a draft job.
Since Jenkins changes are only visible after they are made, I want to share what I plan to change here before doing it. What we currently have is this:
vcbuild.bat build-release %ARCH% upload
and I would change it to this:
if not exist pgo.ps1 goto :no-pgo
if not "%DISTTYPE%"=="release" goto :no-pgo
echo === PGO Build: Step 1 - Build instrumented binary ===
@REM In first PGO build, make x64 binary to generate profdata (Eventually we want to add ARM64 machines for this)
call vcbuild.bat build-release x64 pgo-generate
if errorlevel 1 exit /b %errorlevel%
echo === PGO Build: Step 2 - Run workload and collect profiles ===
powershell -NoProfile -ExecutionPolicy Bypass -File pgo.ps1 -PgoGenNode Release\node.exe -PhaseOnly
if errorlevel 1 exit /b %errorlevel%
echo --- Cleaning instrumented build ---
git clean -fdx -e node.profdata
if errorlevel 1 exit /b %errorlevel%
echo === PGO Build: Step 3 - Build optimized binary ===
call vcbuild.bat build-release %ARCH% pgo-use upload
exit /b %errorlevel%
:no-pgo
echo === Non-PGO Build ===
vcbuild.bat build-release %ARCH% upload
The script checks whether the Node.js being built has PGO enabled, and if so, it uses it for release builds. This way, if/when we backport PGO to LTS versions, they will pick it up for releases without any further changes in Jenkins.
As I've already stated, I tested this and feel confident about enabling it, but please feel free to share any concerns you might have about these changes.
I want to start a discussion about enabling PGO for release builds on Windows. Along with LTO (enabled since v26.3), it will further improve Node.js performance on Windows. While LTO builds took 3-3.5 hours initially, recent changes have reduced them to around 2 hours. Enabling PGO will double that time (2 builds are needed plus running workload scripts in between), but overall it will be a bit longer than what LTO took last week. Additionally, I would only enable PGO for release builds, so nightly and canary builds would be unaffected. I feel confident in enabling this because I've already tested it thoroughly in a draft job.
Since Jenkins changes are only visible after they are made, I want to share what I plan to change here before doing it. What we currently have is this:
vcbuild.bat build-release %ARCH% uploadand I would change it to this:
The script checks whether the Node.js being built has PGO enabled, and if so, it uses it for release builds. This way, if/when we backport PGO to LTS versions, they will pick it up for releases without any further changes in Jenkins.
As I've already stated, I tested this and feel confident about enabling it, but please feel free to share any concerns you might have about these changes.