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Currently when multiple CPUs perform a load-linked/store-conditional sequence, the loads all create a list of reservations which is then scanned when the stores occur. A reservation matching the context and address of the store is sought, BUT all reservations matching the address are also erased at this point. The upshot is that a store-conditional will remove all reservations even if the store itself does not succeed. A livelock was observed using 7-8 CPUs where a thread would erase the reservations of other threads, not succeed, loop and put its own reservation in again only to have it blown by another thread that unsuccessfully now tries to store-conditional -- no forward progress was made, hanging the system. The correct way to do this is to only blow a reservation when a store (conditional or not) actually /occurs/ to its address. One thread always wins (the one that does the store-conditional first).
This is the M5 simulator. For detailed information about building the simulator and getting started please refer to http://www.m5sim.org. Specific pages of interest are: http://www.m5sim.org/wiki/index.php/Compiling_M5 http://www.m5sim.org/wiki/index.php/Running_M5 Short version: 1. If you don't have SCons version 0.98.1 or newer, get it from http://wwww.scons.org. 2. If you don't have SWIG version 1.3.31 or newer, get it from http://wwww.swig.org. 3. Make sure you also have gcc version 3.4.6 or newer, Python 2.4 or newer (the dev version with header files), zlib, and the m4 preprocessor. 4. In this directory, type 'scons build/ALPHA_SE/tests/debug/quick'. This will build the debug version of the m5 binary (m5.debug) for the Alpha syscall emulation target, and run the quick regression tests on it. If you have questions, please send mail to m5-users@m5sim.org WHAT'S INCLUDED (AND NOT) ------------------------- The basic source release includes these subdirectories: - m5: - configs: simulation configuration scripts - ext: less-common external packages needed to build m5 - src: source code of the m5 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. These files for Alpha are collected in a separate archive, m5_system.tar.bz2. This file can he downloaded separately. Depending on the ISA used, M5 may support Linux 2.4/2.6, FreeBSD, and the proprietary Compaq/HP Tru64 version of Unix. We are able to distribute Linux and FreeBSD bootdisks, but we are unable to distribute bootable disk images of Tru64 Unix. If you have a Tru64 license and are interested in obtaining disk images, contact us at m5-users@m5sim.org