XBar.py (10719:b4fc9ad648aa) | XBar.py (10720:67b3e74de9ae) |
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1# Copyright (c) 2012, 2015 ARM Limited 2# All rights reserved. 3# 4# The license below extends only to copyright in the software and shall 5# not be construed as granting a license to any other intellectual 6# property including but not limited to intellectual property relating 7# to a hardware implementation of the functionality of the software 8# licensed hereunder. You may use the software subject to the license --- 52 unchanged lines hidden (view full) --- 61 # 62 # A request incurs the frontend latency, possibly snoop filter 63 # lookup latency, and forward latency. A response incurs the 64 # response latency. Frontend latency encompasses arbitration and 65 # deciding what to do when a request arrives. the forward latency 66 # is the latency involved once a decision is made to forward the 67 # request. The response latency, is similar to the forward 68 # latency, but for responses rather than requests. | 1# Copyright (c) 2012, 2015 ARM Limited 2# All rights reserved. 3# 4# The license below extends only to copyright in the software and shall 5# not be construed as granting a license to any other intellectual 6# property including but not limited to intellectual property relating 7# to a hardware implementation of the functionality of the software 8# licensed hereunder. You may use the software subject to the license --- 52 unchanged lines hidden (view full) --- 61 # 62 # A request incurs the frontend latency, possibly snoop filter 63 # lookup latency, and forward latency. A response incurs the 64 # response latency. Frontend latency encompasses arbitration and 65 # deciding what to do when a request arrives. the forward latency 66 # is the latency involved once a decision is made to forward the 67 # request. The response latency, is similar to the forward 68 # latency, but for responses rather than requests. |
69 frontend_latency = Param.Cycles(3, "Frontend latency") 70 forward_latency = Param.Cycles(4, "Forward latency") 71 response_latency = Param.Cycles(2, "Response latency") | 69 frontend_latency = Param.Cycles("Frontend latency") 70 forward_latency = Param.Cycles("Forward latency") 71 response_latency = Param.Cycles("Response latency") |
72 73 # Width governing the throughput of the crossbar | 72 73 # Width governing the throughput of the crossbar |
74 width = Param.Unsigned(8, "Datapath width per port (bytes)") | 74 width = Param.Unsigned("Datapath width per port (bytes)") |
75 76 # The default port can be left unconnected, or be used to connect 77 # a default slave port 78 default = MasterPort("Port for connecting an optional default slave") 79 80 # The default port can be used unconditionally, or based on 81 # address range, in which case it may overlap with other 82 # ports. The default range is always checked first, thus creating --- 7 unchanged lines hidden (view full) --- 90 cxx_header = "mem/noncoherent_xbar.hh" 91 92class CoherentXBar(BaseXBar): 93 type = 'CoherentXBar' 94 cxx_header = "mem/coherent_xbar.hh" 95 96 # The coherent crossbar additionally has snoop responses that are 97 # forwarded after a specific latency. | 75 76 # The default port can be left unconnected, or be used to connect 77 # a default slave port 78 default = MasterPort("Port for connecting an optional default slave") 79 80 # The default port can be used unconditionally, or based on 81 # address range, in which case it may overlap with other 82 # ports. The default range is always checked first, thus creating --- 7 unchanged lines hidden (view full) --- 90 cxx_header = "mem/noncoherent_xbar.hh" 91 92class CoherentXBar(BaseXBar): 93 type = 'CoherentXBar' 94 cxx_header = "mem/coherent_xbar.hh" 95 96 # The coherent crossbar additionally has snoop responses that are 97 # forwarded after a specific latency. |
98 snoop_response_latency = Param.Cycles(4, "Snoop response latency") | 98 snoop_response_latency = Param.Cycles("Snoop response latency") |
99 100 # An optional snoop filter 101 snoop_filter = Param.SnoopFilter(NULL, "Selected snoop filter") 102 103 system = Param.System(Parent.any, "System that the crossbar belongs to.") 104 105class SnoopFilter(SimObject): 106 type = 'SnoopFilter' 107 cxx_header = "mem/snoop_filter.hh" 108 109 # Lookup latency of the snoop filter, added to requests that pass 110 # through a coherent crossbar. 111 lookup_latency = Param.Cycles(1, "Lookup latency") 112 113 system = Param.System(Parent.any, "System that the crossbar belongs to.") | 99 100 # An optional snoop filter 101 snoop_filter = Param.SnoopFilter(NULL, "Selected snoop filter") 102 103 system = Param.System(Parent.any, "System that the crossbar belongs to.") 104 105class SnoopFilter(SimObject): 106 type = 'SnoopFilter' 107 cxx_header = "mem/snoop_filter.hh" 108 109 # Lookup latency of the snoop filter, added to requests that pass 110 # through a coherent crossbar. 111 lookup_latency = Param.Cycles(1, "Lookup latency") 112 113 system = Param.System(Parent.any, "System that the crossbar belongs to.") |
114 115# We use a coherent crossbar to connect multiple masters to the L2 116# caches. Normally this crossbar would be part of the cache itself. 117class L2XBar(CoherentXBar): 118 # 256-bit crossbar by default 119 width = 32 120 121 # Assume that most of this is covered by the cache latencies, with 122 # no more than a single pipeline stage for any packet. 123 frontend_latency = 1 124 forward_latency = 0 125 response_latency = 1 126 snoop_response_latency = 1 127 128# One of the key coherent crossbar instances is the system 129# interconnect, tying together the CPU clusters, GPUs, and any I/O 130# coherent masters, and DRAM controllers. 131class SystemXBar(CoherentXBar): 132 # 128-bit crossbar by default 133 width = 16 134 135 # A handful pipeline stages for each portion of the latency 136 # contributions. 137 frontend_latency = 3 138 forward_latency = 4 139 response_latency = 2 140 snoop_response_latency = 4 141 142# In addition to the system interconnect, we typically also have one 143# or more on-chip I/O crossbars. Note that at some point we might want 144# to also define an off-chip I/O crossbar such as PCIe. 145class IOXBar(NoncoherentXBar): 146 # 128-bit crossbar by default 147 width = 16 148 149 # Assume a simpler datapath than a coherent crossbar, incuring 150 # less pipeline stages for decision making and forwarding of 151 # requests. 152 frontend_latency = 2 153 forward_latency = 1 154 response_latency = 2 |
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