a701e1fd14
We currently use the traditional SI-like prefixes for to represent binary multipliers in some contexts. This is ambiguous in many cases since they overload the meaning of the SI prefix. Here are some examples of commonly used in the industry: * Storage vendors define 1 MB as 10**6 bytes * Memory vendors define 1 MB as 2**20 bytes * Network equipment treats 1Mbit/s as 10**6 bits/s * Memory vendors define 1Mbit as 2**20 bits In practice, this means that a FLASH chip on a storage bus uses decimal prefixes, but that same flash chip on a memory bus uses binary prefixes. It would also be reasonable to assume that the contents of a 1Mbit FLASH chip would take 0.1s to transfer over a 10Mbit Ethernet link. That's however not the case due to different meanings of the prefix. The quantity 2MX is treated differently by gem5 depending on the unit X: * Physical quantities (s, Hz, V, A, J, K, C, F) use decimal prefixes. * Interconnect and NoC bandwidths (B/s) use binary prefixes. * Network bandwidths (bps) use decimal prefixes. * Memory sizes and storage sizes (B) use binary prefixes. Mitigate this ambiguity by consistently using the ISO/IEC/SI prefixes for binary multipliers for parameters and comments where appropriate. Change-Id: I2d24682d207830f3b7b0ad2ff82b55e082cccb32 Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39576 Reviewed-by: Richard Cooper <richard.cooper@arm.com> Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com> Tested-by: kokoro <noreply+kokoro@google.com>
104 lines
4.2 KiB
Python
104 lines
4.2 KiB
Python
# Copyright (c) 2020 ARM Limited
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# All rights reserved.
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#
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# The license below extends only to copyright in the software and shall
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# not be construed as granting a license to any other intellectual
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# property including but not limited to intellectual property relating
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# to a hardware implementation of the functionality of the software
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# licensed hereunder. You may use the software subject to the license
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# terms below provided that you ensure that this notice is replicated
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# unmodified and in its entirety in all distributions of the software,
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# modified or unmodified, in source code or in binary form.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met: redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer;
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# redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution;
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# neither the name of the copyright holders nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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from m5.params import *
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from m5.proxy import *
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from m5.objects.MemInterface import MemInterface
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from m5.objects.DRAMInterface import AddrMap
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# The following interface aims to model byte-addressable NVM
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# The most important system-level performance effects of a NVM
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# are modeled without getting into too much detail of the media itself.
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class NVMInterface(MemInterface):
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type = 'NVMInterface'
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cxx_header = "mem/mem_interface.hh"
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# NVM DIMM could have write buffer to offload writes
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# define buffer depth, which will limit the number of pending writes
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max_pending_writes = Param.Unsigned("1", "Max pending write commands")
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# NVM DIMM could have buffer to offload read commands
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# define buffer depth, which will limit the number of pending reads
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max_pending_reads = Param.Unsigned("1", "Max pending read commands")
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# timing behaviour and constraints - all in nanoseconds
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# define average latency for NVM media. Latency defined uniquely
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# for read and writes as the media is typically not symmetric
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tREAD = Param.Latency("100ns", "Average NVM read latency")
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tWRITE = Param.Latency("200ns", "Average NVM write latency")
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tSEND = Param.Latency("15ns", "Access latency")
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two_cycle_rdwr = Param.Bool(False,
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"Two cycles required to send read and write commands")
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# NVM delays and device architecture defined to mimic PCM like memory.
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# Can be configured with DDR4_2400 sharing the channel
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class NVM_2400_1x64(NVMInterface):
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write_buffer_size = 128
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read_buffer_size = 64
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max_pending_writes = 128
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max_pending_reads = 64
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device_rowbuffer_size = '256B'
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# 8X capacity compared to DDR4 x4 DIMM with 8Gb devices
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device_size = '512GiB'
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# Mimic 64-bit media agnostic DIMM interface
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device_bus_width = 64
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devices_per_rank = 1
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ranks_per_channel = 1
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banks_per_rank = 16
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burst_length = 8
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two_cycle_rdwr = True
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# 1200 MHz
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tCK = '0.833ns'
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tREAD = '150ns'
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tWRITE = '500ns';
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tSEND = '14.16ns';
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tBURST = '3.332ns';
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# Default all bus turnaround and rank bus delay to 2 cycles
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# With DDR data bus, clock = 1200 MHz = 1.666 ns
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tWTR = '1.666ns';
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tRTW = '1.666ns';
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tCS = '1.666ns'
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