aae1ec8a90
Modify second chance replacement policy so that entries are inserted without a second chance. Previously, the second chance bit was set to true when a cache line was inserted. So the cache line would gain its second chance when inserting. This is wrong because the cache block will only get a second chance when it hits. Here's a quoted citation for the second chance replacement policy: "Whenever the algorithm examines a page entry, it extracts the associated usage bit and enters it into the high-order position of a k-bit shift register after shifting the contents of the register one bit-position lower. Then if the shift register is nonzero, the page is retained; if the shift register is zero, the page is replaced by the new page. In either case the usage bit for the page is turned off and the circular list pointer is advanced." (A Paging Experiment with the Multics System, FJ Corbato, 1968) Change-Id: I0d07e56aa16c67dd36e0d490c3f457f91e46f320 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20882 Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br> 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.