No description
db85ddca1a
This patch changes how the crossbar classes deal with responses. Instead of forwarding responses directly and burdening the neighbouring modules in paying for the latency (through the pkt->headerDelay), we now queue them before sending them. The coherency protocol is not affected as requests and any snoop requests/responses are still passed on in zero time. Thus, the responses end up paying for any header delay accumulated when passing through the crossbar. Any latency incurred on the request path will be paid for on the response side, if no other module has dealt with it. As a result of this patch, responses are returned at a later point. This affects the number of outstanding transactions, and quite a few regressions see an impact in blocking due to no MSHRs, increased cache-miss latencies, etc. Going forward we should be able to use the same concept also for snoop responses, and any request that is not an express snoop. |
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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.