messier

The messier library models a non-volatile memory (NVM) DIMM architecture. The library can be used in conjunction with other SST core and memory system models to simulate an architecture integrating NVDIMMs. Messier is supported as a memory model for memHierarchy-based memory architectures.

At a Glance

Source Code: sst-elements/.../messier  
SST Name: messier  
Maturity Level: Prototype (2)  
Development Path: Active  
Last Released: SST 16.1

Required dependencies

None

Optional dependencies

None

Elements

Use sst-info Messier or sst-info Messier.Messier to see its parameters, ports, and statistics. The element library is named Messier (capitalized), unlike the directory.

Library	Element	Type	Description
Messier	Messier	Component	NVM DIMM model with banks, a write buffer, and power/current limits on concurrent reads and writes. Can be loaded as just "Messier"

To use Messier as main memory, set a memHierarchy.MemController's backend to memHierarchy.Messier and connect the backend's nvm_link port to the Messier component's bus port.

A Miranda core with Messier NVM as main memory (based on messier/tests/gupsgen.py)

import sst

memory_mb = 128

# Core and L1 cache
cpu = sst.Component("cpu", "miranda.BaseCPU")
gen = cpu.setSubComponent("generator", "miranda.GUPSGenerator")
gen.addParams({
    "count" : 10000,
    "max_address" : (memory_mb // 2) * 1024 * 1024,
})

l1cache = sst.Component("l1cache", "memHierarchy.Cache")
l1cache.addParams({
    "access_latency_cycles" : "2",
    "cache_frequency" : "2 Ghz",
    "replacement_policy" : "lru",
    "coherence_protocol" : "MESI",
    "associativity" : "4",
    "cache_line_size" : "64",
    "L1" : "1",
    "cache_size" : "8KB",
})

# Memory controller with the Messier backend
memctrl = sst.Component("memory", "memHierarchy.MemController")
memctrl.addParams({
    "clock" : "1024 MHz",
    "backing" : "none",
    "addr_range_start" : 0,
})
backend = memctrl.setSubComponent("backend", "memHierarchy.Messier")
backend.addParams({ "mem_size" : "1024MB" })

# NVM model
nvm = sst.Component("NVMmemory", "Messier.Messier")
nvm.addParams({
    "clock" : "1GHz",
    "tCL" : 30,
    "tRCD" : 300,
    "tCL_W" : 1000,
    "write_buffer_size" : 32,
    "flush_th" : 90,
    "num_banks" : 32,
    "max_outstanding" : 32,
    "max_current_weight" : 160,
    "read_weight" : 5,
    "write_weight" : 50,
    "max_writes" : 4,
})

sst.Link("cpu_l1").connect((cpu, "cache_link", "1000ps"), (l1cache, "highlink", "1000ps"))
sst.Link("l1_mem").connect((l1cache, "lowlink", "50ps"), (memctrl, "highlink", "50ps"))
sst.Link("backend_nvm").connect((backend, "nvm_link", "50ps"), (nvm, "bus", "50ps"))

# Print NVM statistics at the end of the run
sst.setStatisticLoadLevel(1)
nvm.enableAllStatistics()

Additional Documentation

A technical report on the messier library is available here.