xref: /gem5/ext/drampower/ChangeLog

Change Log:

DRAMPower v4.0 - *  DRAMPower can now be compiled as a library. This enables a user
	            to access the tool through an API and log commands and their
	            corresponding time stamps, removing the need to store large
	            command traces on disk. In addition, cycle counting variables
	            have been changed to int64 to support longer simulations.
	            The library can be compiled without Xerces to remove an optional 
	            dependency and reduce the size of the binary.
	             *  Improved robustness. The latest build is automatically checked 
	            out on a test server, compiled, and tested to verify that the 
	            output matches an expected reference. The code is also compiled
	            with a large number of warning flags enabled and treats all 
	            warnings as errors.
	         *  Bug fix: Fixed bug in io/termination energy calculation.
	         *  Bug fix: Fixed bug in calculation of auto precharge cycle.

DRAMPower v3.1 - *  Added IO and Termination Power measures from Micron's DRAM Power 
		    Calculator, for all supported DRAM generations. In the case of 
		    Wide IO DRAMs, these measures are already included in the provided
		    current specifications. This feature enables support for multi-rank 
		    DRAM DIMMs (DDR2/3/4) and stacking of multiple Wide IO DRAM dies 
		    (equivalent to ranks). To indicate use of multi-rank DRAMs or 
		    multiple Wide IO DRAM dies/layers, the 'nbrOfRanks' parameter in 
		    the memory specification XMLs can be employed. Note: The DRAM 
		    command scheduler does not support multi-rank/multi-die DRAMs yet.
		    Only the power estimation component of DRAMPower has been updated 
		    to support them. The current measures for dual-rank DRAMs only
		    reflect those for the active rank and not the idle rank. The 
		    default state of the idle rank is assumed to be the same as the 
		    current memory state, for background power estimation. Hence,
		    rank information in the command trace is not required.
		 *  Added warning messages: New warning messages are provided, to 
		    identify if the memory or bank state is inconsistent in the 
		    user-defined traces. Towards this, a state check is performed on 
		    every memory command issued.
		 *  Improved run-time options: Users can now point directly to the 
		    memory specification XML, instead of just the memory ID. Also, 
		    users can optionally include IO and termination power estimates 
		    (for both single and dual rank DRAMs) using '-r' flag in the 
		    command line options.
		 *  Bug fixes: (1) Refresh handler in the DRAM Command Scheduler was 
		    kept ON in the Self-Refresh mode, when it can be turned OFF. This 
		    bug has now been fixed. (2) Precharge All (PREA) always considered 
		    precharging of all banks. It has now been modified to consider 
		    precharging of the open/active banks alone. 

DRAMPower v3.0 - *  Added support for LPDDR3 and DDR4 memories, besides the already
                    supported DDR2/DDR3, LPDDR/LPDDR2 and WIDE IO DRAM memories.
                 *  Added DRAM Command Scheduler: To support users of DRAMPower 
		    without access to DRAM controllers, we have added a simple DRAM 
		    command scheduler that dynamically schedules DRAM commands as if 
		    it were a memory controller. The scheduler assumes closed-page 
		    policy, employs ASAP scheduling for DRAM commands (i.e. schedules 
		    commands as soon as timing constraints are met), performs FCFS 
		    scheduling on DRAM transactions and supports all the different 
		    DRAM generations supported by the power model. The generated DRAM 
		    command schedule is also analyzable for real-time applications. 
		    Users can also select speculative usage of power-down or 
		    self-refresh modes (if needed) for idle periods between 
		    transactions. It should be noted that using this command scheduler 
		    is optional and it can be (de-)selected during run-time and users 
		    can switch back to the previously used DRAM command interface as 
		    in the earlier versions.
                 *  Improved run-time options: Users can specify the memory and the 
		    trace file to be used by DRAMPower using command line options. 
		    Additionally, if the DRAM command scheduler is being used, the 
		    users can specify the degree of bank interleaving required, the 
		    request size and power-down or self-refresh options. Also, for 
		    DDR4 memories the bank group interleaving can be specified using 
		    command line options.
                 *  Bug fixes: (1) For command traces ending with a RD/WR/RDA/WRA 
		    command, the tool did not consider completion of operations when 
		    estimating the total trace energy. The missing cycles are now 
		    taken into account.
                    (2) The IDD5 (REF current) specification for WIDE IO SDR memory
                    specifications only included 2 banks for refreshes instead of all 
		    four. We would like to thank David Roberts from AMD for spotting 
		    the issue in our DATE'13 article. These measures have been updated.
                    (3) When estimating precharge cycle for commands with 
		    auto-precharge, (RDA/WRA), the command analysis tool employed the 
		    last activation cycle in the entire DRAM instead of the particular 
		    DRAM bank. This bug has been fixed in this release.

DRAMPower v2.1 - *  Added support for variation-aware power estimation, for a 
    		    selection of DDR3 memories manufactured using 50nm process 
		    technology, based on the Monte-Carlo analysis presented in our 
		    DAC'13 article.

DRAMPower v2.0 - *  Added support for LPDDR/LPDDR2 and WIDE IO DRAM memories, besides 
		    the already supported DDR2/DDR3 memories.
                 *  Faster analysis: The trace analysis component in DRAMPower v2.0
                    triggers the evaluation only during memory state transitions
                    (between active, precharged, active and precharged power-down,
                    refresh, self-refresh and power-up states) and not on every clock
                    cycle, as was the case till the last version. This optimization 
		    speeds up the power simulations using DRAMPower by several times 
		    over cycle-accurate analysis, resulting in fast power analysis, 
		    without affecting the accuracy of the trace analysis or the 
		    reported power and energy estimates.
		 *  Verification effort: Our power model was verified by the
                    Microelectronic System Design group at TU Kaiserslautern using
                    circuit-level SPICE simulations of a DRAM cross-section. As a 
		    result of this verification effort, a couple of power equations 
		    have been modified for Refresh and Self-refresh operations. The 
		    difference between the power and energy estimates reported by our 
		    updated model and the equivalent circuit-level simulations is 
		    < 2% for all memory operations of any granularity for all memories 
		    supported by DRAMPower.

DRAMPower v1.2 - *  Supports different power-down and self-refresh modes in DDR2 and 
		    DDR3 DRAM memories.
                 *  Bug fix: Refresh power consumption equation in DRAMPower v1,
                    incorrectly subtracted IDD2n (precharge background current) 
		    instead of IDD3n (active background current) from IDD5 (total 
		    refresh current). This error has been rectified in this version.

DRAMPower v1.0 - *  Performs cycle-accurate memory command trace analysis and estimates
                    power and energy consumption numbers for the trace.
                 *  It supports the basic memory operations like read, write, refresh,
                    activate and (auto) precharge in DDR2 and DDR3 memories.