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This patch adds the functionality to properly track CleanEvicts and Writebacks in the snoop filter. Previously there were no CleanEvicts, and Writebacks did not send up snoops to ensure there were no copies in caches above. Hence a writeback could never erase an entry from the snoop filter. When a CleanEvict message reaches a snoop filter, it confirms that the BLOCK_CACHED flag is not set and resets the bits corresponding to the CleanEvict address and port it arrived on. If none of the other peer caches have (or have requested) the block, the snoop filter forwards the CleanEvict to lower levels of memory. In case of a Writeback message, the snoop filter checks if the BLOCK_CACHED flag is not set and only then resets the bits corresponding to the Writeback address. If any of the other peer caches have (or has requested) the same block, the snoop filter sets the BLOCK_CACHED flag in the Writeback before forwarding it to lower levels of memory heirarachy.
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.