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Only a small quantity of prefetches were issued, as the positive feedback mechanism was not implemented. This commit adds a new action po_observeHit, which notifies the RubyPrefetcher of successful prefetches and resets the prefetch flag. When a cache line was replaced by a prefetch, the wrong queue could be stalled. This commit adds a new event PF_L1_Replacement, which stalls the correct queue. The behavior when receiving a prefetch or instruction fetch while in PF_IS_I (prefetch caused GETs, but got invalidated before the response was received) was undefined. This was changed to drop the prefetch request or change the state to non-prefetch, respectively. This behavior is analogous to IS_I (non-prefetch caused GETs, but got invalidated before the response was received) and the data case, respectively. In my local branch a major (20+%) performance increase can be observed in SPEC2006 gobmk and leslie3d when enabling the prefetcher. Some other benchmarks like bwaves, GemsFDTD, sphinx and wrf show smaller (~10%) performance increases. Unfortunately, the performance in most other SPEC benchmarks is still poor, most likely as the prefetcher does not detect strides fast/often enough. In order to push the change timely (most benchmarks have runtimes in the order of days on my machine even with the smallest parameters) after checkout, I have only run gobmk with the base repository + this commit. The results match those of my local branch. Change-Id: I9903a2fcd02060ea5e619b409f31f7d6fac47ae8 Reviewed-on: https://gem5-review.googlesource.com/8801 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Swapnil Haria <swapnilster@gmail.com> Maintainer: Jason Lowe-Power <jason@lowepower.com>
This is the gem5 simulator. The main website can be found at http://www.gem5.org A good starting point is http://www.gem5.org/Introduction, and for more information about building the simulator and getting started please see http://www.gem5.org/Documentation and http://www.gem5.org/Tutorials. To build gem5, you will need the following software: g++ or clang, Python (gem5 links in the Python interpreter), SCons, SWIG, zlib, m4, and lastly protobuf if you want trace capture and playback support. Please see http://www.gem5.org/Dependencies for more details concerning the minimum versions of the aforementioned tools. Once you have all dependencies resolved, type 'scons build/<ARCH>/gem5.opt' where ARCH is one of ALPHA, ARM, NULL, MIPS, POWER, SPARC, or X86. This will build an optimized version of the gem5 binary (gem5.opt) for the the specified architecture. See http://www.gem5.org/Build_System for more details and options. With the simulator built, have a look at http://www.gem5.org/Running_gem5 for more information on how to use gem5. The basic source release includes these subdirectories: - configs: example simulation configuration scripts - ext: less-common external packages needed to build gem5 - src: source code of the gem5 simulator - system: source for some optional system software for simulated systems - tests: regression tests - util: useful utility programs and files To run full-system simulations, you will need compiled system firmware (console and PALcode for Alpha), kernel binaries and one or more disk images. Please see the gem5 download page for these items at http://www.gem5.org/Download If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.