1. Computers
  2. Display Drivers
  3. Graphics Cards
  4. Memory
  5. Motherboards
  6. Processors
  7. Software
  8. Storage
  9. Operating Systems


Facebook RSS Twitter Twitter Google Plus


Phoronix Test Suite

OpenBenchmarking.org

AutoFDO Optimizations For The GCC Compiler

Compiler

Published on 30 September 2012 06:58 AM EDT
Written by Michael Larabel in Compiler
3 Comments

A patch has emerged that provides "AutoFDO" support for the GCC compiler for automated feedback-directed optimizations.

Dehao Chen of Google published an AutoFDO implementation to the GCC mailing list on Friday.
This patch implements the fine-graind AutoFDO optimizations for GCC. It uses linux perf to collect sample profiles, and uses debug info to represent the profile. In GCC, it uses the profile to annotate CFG to drive FDO. This can bring 50% to 110% of the speedup derived by traditional instrumentation based FDO. (Average is between 70% to 80% for many CPU intensive applications). Comparing with traditional FDO, AutoFDO does not require instrumentation. It just need to have an optimized binary with debug info to collect the profile.

This patch has passed bootstrap and gcc regression tests as well as tested with crosstool. Okay for google branches?

If people in up-stream find this feature interesting, I'll spend some time to port this to trunk and try to opensource the tool to generate profile data file.
So this implementation is also faster than the traditional Feedback Directed Optimization (FDO) support currently found in GCC.

Up until now traditional FDO has required running the specially-created binary manually to collect sample/training data that can then be passed back to the GNU Compiler Collection for producing a more-optimized binary on an application-specific case. Among the optimizations being dealt with here are instruction scheduling, basic block re-ordering, function splitting, and register allocation.

Let's hope it makes it into GCC trunk! Until then, the patch is on gcc-patches.

About The Author
Michael Larabel is the principal author of Phoronix.com and founded the web-site in 2004 with a focus on enriching the Linux hardware experience and being the largest web-site devoted to Linux hardware reviews, particularly for products relevant to Linux gamers and enthusiasts but also commonly reviewing servers/workstations and embedded Linux devices. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics hardware drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated testing software. He can be followed via and or contacted via .
Latest Articles & Reviews
  1. Ubuntu vs. Fedora Linux On Lenovo's X1 Carbon With Core i7 Broadwell
  2. Ubuntu 15.04 Is The Easy Path To Better Performance On Intel Broadwell
  3. NVIDIA's Latest Maxwell Line-Up Against AMD With Catalyst On Linux
  4. Preliminary Tests Of Intel Sandy Bridge & Ivy Bridge vs. Broadwell
  5. AMD FX-8320E Performance On Linux
  6. Linux Compiler Benchmarks Of LLVM Clang 3.5 vs. LLVM Clang 3.6-rc1
Latest Linux News
  1. Libinput 0.9 Adds Support For Hovering Fingers On Touchpads
  2. Free Software Foundation Endorses Another (Outdated) Laptop
  3. DNF Plugins Extend The Functionality Of Fedora's Yum Successor
  4. LibreOffice 4.4 Released With Better OOXML Support, UI Improvements
  5. Inkscape 0.91 Goes Through C++ Code Conversion, New Cairo Rendering, OpenMP Filters
  6. New Mesa Patch To Improve CPU-Bound Applications
  7. LLVM Adds Options To Do Fuzz Testing
  8. Coreboot Now Supports Another Dual-Socket AMD Motherboard
  9. Atomic Mode-Setting/Display Support Progresses In Linux 3.20
  10. NVIDIA 340.76 Brings Three Stable Fixes
Most Viewed News This Week
  1. PlayStation 4 System Compiler Support Landing In LLVM
  2. LibreOffice 4.4 Is Coming Soon With New Features
  3. Linux "GHOST" Vulnerability Hits Glibc Systems
  4. My Initial Intel Broadwell Linux Experience With The ThinkPad X1 Carbon
  5. Broadwell Linux Ultrabook Running MUCH Cooler Than Haswell
  6. LZHAM 1.0 Lossless Data Compression Codec Released
  7. Linux Users Upset By Chromium's Busted HiDPI Support
  8. Faster VP9 Decoding Is On The Horizon