gem5-nvmain-hybrid-simulator

1. DRAM-NVM Hybrid-Simulator

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1.1 Full System Simultor : gem5

• Home Page of Simulator：http://www.gem5.org/Main_Page

1.2 Memory System Simulator: NVMain

• Home Page of Simulator: http://wiki.nvmain.org/

1.3 how to attach nvmain with gem5

    (1) environment requirement

• python version < 3.0
• scons >= 0.98.1
• gcc >= 4.6.0;

(2) compile gem5 with nvmain (patch file can be found in gem5-stable/final_patch/nvmain-classic-gem5-9850)

• patch gem5 with nvmain patch file : patch -p1 < final_patch/nvmain-classic-gem5-9850

• compile with scons : scons EXTRAS=nvmain-path -jn (n represents compiling threads num)

    (3) run system with nvmain memory
  

• you can refer to example in directory rapp-test/gcc:--mem-type=nvmain --nvmain-config=nvmain-config-file-path

2. Cache Optimization Module in gem5-nvmain-hybrid-simulator

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（1）Architecture and Principle of Cache Optimization in DRAM-PCM hybrid memory 

• adjust cache replacement policy according to cache miss penalty in DRAM-PCM hybrid memory system , for example: evict data block in LLC cache which fetched from PCM is expensive than data block fetched from DRAM . When evicting cache block from LLC cache , evict data block from DRAM first;

• recalculate cache replacement priority according to penalty of cache miss in memory system and reuse probability of cache block;

    （2）related source code
  

• gem5-stable/src/mem/cache/tags/

3. Rank-Based-Page-Placement Module in hybrid simulator implemented by multi-level-queue

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    （1）Principle of Rank-Based-Page-Placement Strategy

• classfy memory pages into hot-pages and cold-pages according to access time;

• page access information is managed by multi-level-queue;

    （2）related source code
  

• nvmain/Utils/MultiQueMigrator/

• Decoders/Migrator/

• configuration file example: Config/Hybrid_example.config

• simple example scripts running CPU SPEC2006 benchmarks are placed in directory: gem5-stable/rapp-test

4. Programmer-Specific-Page-Migration in Hybrid memory system

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