PGO - AshokBhat/notes GitHub Wiki

PGO (Profile Guided Optimization)

• (aka Pogo, FDO, -fprofile-use)

Steps

• Instrument for profiling
• Run that instrumented executable in various scenarios
• Use the resulting performance profile to guide the compiler.

Usage

Microsoft

• Microsoft Windows heavily utilizes both LTO and PGO
• Windows sees 5-20% improvements from PGO
• https://lpc.events/event/7/contributions/771/attachments/630/1193/Exploring_Profile_Guided_Optimization_of_the_Linux_Kernel.pdf

Google Chrome

• Uses PGO on x86
• https://blog.chromium.org/2020/08/chrome-just-got-faster-with-profile.html

Apple

• Apple uses LTO extensively internally
• Typically 10% faster than executables from regular Release builds
• Multiplies with PGO
• Reduces code size when optimizing for size
• https://devstreaming-cdn.apple.com/videos/wwdc/2016/405i2ilotov3bazyei1/405/405_whats_new_in_llvm.pdf (Slide 107)

See also

• GNU Toolchain
• LLVM
• LTO