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1dc16aff24
Added power-down state transitions to the DRAM controller model. Added per rank parameter, outstandingEvents, which tracks the number of outstanding command events and is used to determine when the controller should transition to a low power state. The controller will only transition when there are no outstanding events scheduled and the number of command entries for the given rank is 0. The outstandingEvents parameter is incremented for every RD/WR burst, PRE, and REF event scheduled. ACT is implicitly covered by RD/WR since burst will always issue and complete after a required ACT. The parameter is decremented when the event is serviced (completed). The controller will automatically transition to ACT power down, PRE power down, or SREF. Transition to ACT power down state scheduled from: 1) The RespondEvent, where read data is received from the memory. ACT power-down entry will be scheduled when one or more banks is open, all commands for the rank have completed (no more commands scheduled), and there are no commands in queue for the rank Transition to PRE power down scheduled from: 1) respondEvent, when all banks are closed, all commands have completed, and there are no commands in queue for the rank 2) prechargeEvent when all banks are closed, all commands have completed, and there are no commands in queue for the rank 3) refreshEvent, after the refresh is complete when the previous state was ACT power-down 4) refreshEvent, after the refresh is complete when the previous state was PRE power-down and there are commands in the queue. Transition to SREF will be scheduled from: 1) refreshEvent, after the refresh is completes when the previous state was PRE power-down with no commands in queue Power-down exit commands are scheduled from: 1) The refreshEvent, prior to issuing a refresh 2) doDRAMAccess, to wake-up the rank for RD/WR command issue. Self-refresh exit commands are scheduled from: 1) The next request event, when the queue has commands for the rank in the readQueue or there are commands for the rank in the writeQueue and the bus state is WRITE. Change-Id: I6103f660776e36c686655e71d92ec7b5b752050a Reviewed-by: Radhika Jagtap <radhika.jagtap@arm.com> |
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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.