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prospero

Prospero is a trace-based core model. The core models memory instructions only. Multiple Prospero cores can be used in the same simulation, each running independent trace files, to model a multicore architecture. A Pintool for collecting traces from x86 binaries is included. Prospero interfaces with memory via the SST::StandardMem interface.

At a Glance

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

Required dependencies: None​

Optional dependencies: None​

  • Pin If available, the included Pintool can be used to generate a trace for simulation, otherwise a trace must be acquired separately.
  • zlib Enables reading and/or generating a compressed execution trace

Trace Format​

Text​

Each line of a text trace represents a separate memory access. The format is cycles type address length where:

  • cycles Minimum cycle count at which the request can be issued
  • type R (read) or W (write). Not case-sensitive.
  • address Memory address, as a decimal integer
  • length Number of bytes to read or write

Binary​

Each record in a binary trace consists of the same four fields as the text trace, except that they are represented as a byte array (char*). There is no separator between records and the size of each field is:

  • cycles uint64_t
  • type char
  • address uint64_t
  • length uint32_t

Compressed​

If zlib is available, use of compressed text or binary traces is supported.

Elements​

Use sst-info prospero or sst-info prospero.<element> to see each element's parameters, ports, and statistics.

LibraryElementTypeDescription
prosperoprosperoCPUComponentCore that replays a memory trace through a StandardMem interface; the trace reader is selected with the reader parameter, and its parameters are given as readerParams.*
prosperoProsperoTextTraceReaderSubComponentDefault reader, for text traces (see Text)
prosperoProsperoBinaryTraceReaderSubComponentReader for binary traces (see Binary)
prosperoProsperoCompressedBinaryTraceReaderSubComponentReader for compressed binary traces. Built only when zlib is found

The example below replays a text trace, e.g. a file prospero.trace containing:

prospero.trace
0 R 4096 8
10 W 8192 8
20 R 4160 8
30 W 8256 8
Replaying a text trace through an L1 cache (based on prospero/tests/array/trace-text.py)
import sst

sst.setProgramOption("timebase", "1ps")

# Trace replay core
cpu = sst.Component("cpu", "prospero.prosperoCPU")
cpu.addParams({
    "reader" : "prospero.ProsperoTextTraceReader",
    "readerParams.file" : "prospero.trace",
})

# L1 cache and memory
l1cache = sst.Component("l1cache", "memHierarchy.Cache")
l1cache.addParams({
    "access_latency_cycles" : "1",
    "cache_frequency" : "2 Ghz",
    "replacement_policy" : "lru",
    "coherence_protocol" : "MESI",
    "associativity" : "8",
    "cache_line_size" : "64",
    "L1" : "1",
    "cache_size" : "64 KB",
})
memctrl = sst.Component("memory", "memHierarchy.MemController")
memctrl.addParams({ "clock" : "1GHz" })
memory = memctrl.setSubComponent("backend", "memHierarchy.simpleMem")
memory.addParams({
    "access_time" : "1000 ns",
    "mem_size" : "4096MiB",
})

sst.Link("cpu_l1").connect((cpu, "cache_link", "1000ps"), (l1cache, "highlink", "1000ps"))
sst.Link("l1_mem").connect((l1cache, "lowlink", "50ps"), (memctrl, "highlink", "50ps"))