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gem5 RubyPort： mem_request_port作用与连接 simple-MI_example.py

news 2025/9/12 21:34:21

简介

回答这个问题：RubyPort的口下，一共定义了六个口，分别是mem_request_port，mem_response_port，pio_request_port，pio_response_port，in_ports, interrupt_out_ports，他们分别有什么用，应该怎么接

overview是下面这个图。
在这里插入图片描述

以一个简单的l1 cache为例子

https://www.gem5.org/documentation/learning_gem5/part3/simple-MI_example/

首先是l1cache对子函数的连接

class L1Cache(L1Cache_Controller):。。。def connectQueues(self, ruby_system):。。。self.mandatoryQueue = MessageBuffer()self.requestFromCache = MessageBuffer(ordered = True)self.requestFromCache.master = ruby_system.network.slaveself.responseFromCache = MessageBuffer(ordered = True)self.responseFromCache.master = ruby_system.network.slaveself.forwardToCache = MessageBuffer(ordered = True)self.forwardToCache.slave = ruby_system.network.masterself.responseToCache = MessageBuffer(ordered = True)self.responseToCache.slave = ruby_system.network.master

然后是system对子函数的连接操作

step 1对一个RubySystem延伸的类，他的controller是python自己定义的。
step 2 这里它简化了一下，只有一个dir controller,也就是只有一个memory ctrl,但是 l1cache还是每个cpu都有一个的。
step3 创建了self.controller之后，并没有互联！这个rubysystem调用了自己的子类的子函数连接了网络和controllers。
step4 显式的连接cpu 与ruby system的 sequencer。

#step 1
class MyCacheSystem(RubySystem):#step 2 self.controllers = [L1Cache(system, self, cpu) for cpu in cpus] + [ DirController(self, system.mem_ranges, mem_ctrls) ]#step 3self.network.connectControllers(self.controllers)#step 4# Connect the cpu's cache, interrupt, and TLB ports to Rubyfor i,cpu in enumerate(cpus):cpu.icache_port = self.sequencers[i].slavecpu.dcache_port = self.sequencers[i].slaveisa = buildEnv['TARGET_ISA']if isa == 'x86':cpu.interrupts[0].pio = self.sequencers[i].mastercpu.interrupts[0].int_master = self.sequencers[i].slavecpu.interrupts[0].int_slave = self.sequencers[i].masterif isa == 'x86' or isa == 'arm':cpu.itb.walker.port = self.sequencers[i].slavecpu.dtb.walker.port = self.sequencers[i].slave

然后我们看看每一步怎么连接的细节：

step3 network.connectControllers(self.controllers)

先看看前置的一些条件

这里的self.controllers 创建了64个L1缓存控制器，每个控制器对应一个CPU，加上一个目录控制器。因此，controllers 列表总共包含65个控制器。
这里有一个不是很常规的情况：每个router连接了一个controller,也就是有65个router。正常应该是64个router对应64个cpu的，这里为了简便，直接每个controller分配一个router。同时，router间的互连也简化为crossbar,每个router连接了剩下所有的64个 router

 # Create one router/switch per controller in the systemself.routers = [Switch(router_id = i) for i in range(len(controllers))]#outer间的互连也简化为crossbar,每个router连接了剩下所有的router，例如64个routerfor ri in self.routers:for rj in self.routers:if ri == rj: continue # Don't connect a router to itself!link_count += 1self.int_links.append(SimpleIntLink(link_id = link_count,src_node = ri,dst_node = rj))

这些前置条件过后，看怎么连接controller和router的：

def connectControllers(self, controllers):"""Connect all of the controllers to routers and connect the routerstogether in a point-to-point network."""# Create one router/switch per controller in the systemself.routers = [Switch(router_id = i) for i in range(len(controllers))]# Make a link from each controller to the router. The link goes# externally to the network.self.ext_links = [SimpleExtLink(link_id=i, ext_node=c,int_node=self.routers[i])for i, c in enumerate(controllers)]# Make an "internal" link (internal to the network) between every pair# of routers.link_count = 0self.int_links = []for ri in self.routers:for rj in self.routers:if ri == rj: continue # Don't connect a router to itself!link_count += 1self.int_links.append(SimpleIntLink(link_id = link_count,src_node = ri,dst_node = rj))

把这些代码画成图如下：

                +----------------+|     CPU 0      || icache_port    || dcache_port    |+----------------+|v+----------------+| RubySequencer  |+----------------+|v+---------------+|   L1 Cache   |			 |   L1 Cache.sub   |	|viaSimpleExtLin|          |responseFromCache.master|   |forwardToCache.slave|                |responseToCache.slave|+---------------+         	  +---------------+          +---------------+                           +---------------+  | 							 |                          |                                            |v  							 v                          v                                            v+----------------+          +----------------+  |rubysystem.network.Router 0|       |rubysystem.network.slave|   |rubysystem.network.slave|           |ruby_system.network.master       |                            +----------------+		    +----------------+

                ... (多个类似的组件重复上述连接关系) ...+----------------+|     CPU 63     || icache_port    || dcache_port    |+----------------+|v+----------------+| RubySequencer  |+----------------+|v+---------------+|   L1 Cache   |+---------------+|v+----------------+|   Router 63    |+----------------+第65个router比较特殊，在这个简化的实例里没有连接l1而是连接了dircontroller.同时每个router之间都是连接的。+----------------+|   Router 64    |+----------------+^            ||            v+----------------+|   DirController|+----------------+

代码和图联合分析

按照https://www.gem5.org/documentation/learning_gem5/part3/simple-MI_example/ 的顺序，

连接l1 cache与router

rubysystem 创建了一堆controller，随后创建了sequencer但是还没连，然后调用network。connectController连接了controlle和router,

 # Create the network and connect the controllers.# NOTE: This is quite different if using Garnet!self.network.connectControllers(self.controllers)self.network.setup_buffers()

也就是在这里插入图片描述 l1cache和network.router通过simpleextlink相连的。

连接cpu 与sequencer

随后，rybysystem 显式的连接了之前创建的sequence和 cpu的interrupt 和itb.walker.port.

 # Connect the cpu's cache, interrupt, and TLB ports to Rubyfor i,cpu in enumerate(cpus):cpu.icache_port = self.sequencers[i].slavecpu.dcache_port = self.sequencers[i].slaveisa = buildEnv['TARGET_ISA']if isa == 'x86':cpu.interrupts[0].pio = self.sequencers[i].mastercpu.interrupts[0].int_master = self.sequencers[i].slavecpu.interrupts[0].int_slave = self.sequencers[i].masterif isa == 'x86' or isa == 'arm':cpu.itb.walker.port = self.sequencers[i].slavecpu.dtb.walker.port = self.sequencers[i].slave

图里也就是连接这一部分：
在这里插入图片描述

连接l1cache 和rubysystem.networ

这里是隐藏在l1初始化的时候，创建l1cache需要初始化，（对这个python文件）初始化的时候l1cache就传递进来了rubysystem这个对象。

self.connectQueues(ruby_system)

然后l1cache连接了rubyssytem的master和slaveport.现在叫out_port 和in_port 。

 def connectQueues(self, ruby_system):"""Connect all of the queues for this controller."""self.mandatoryQueue = MessageBuffer()self.requestFromCache = MessageBuffer(ordered = True)self.requestFromCache.master = ruby_system.network.slaveself.responseFromCache = MessageBuffer(ordered = True)self.responseFromCache.master = ruby_system.network.slaveself.forwardToCache = MessageBuffer(ordered = True)self.forwardToCache.slave = ruby_system.network.masterself.responseToCache = MessageBuffer(ordered = True)self.responseToCache.slave = ruby_system.network.master#小插曲： master和slave的说法已经被弃用了 by src/mem/ruby/network/Network.py#in_port = VectorResponsePort("CPU input port")#slave = DeprecatedParam(in_port, "`slave` is now called `in_port`")#out_port = VectorRequestPort("CPU output port")#master = DeprecatedParam(out_port, "`master` is now called `out_port`")

图里是这一部分，描述的l1的cache的子成员直接和network相连。
在这里插入图片描述

关键问题：这些port结构连上了，但是属于哪些类型的rubyport？

rubyport。hh里有六种类型，这些结构上相连的port各自属于哪些类型？我们一个个搜索从结构上看过来

RubySequencer

代码用的self.sequencers[i].master/slave,其中 self.sequencers = [RubySequencer(version = i,。。。
RubySequencer 从哪里来的呢？
在src/mem/ruby/system/Sequencer.py找到了 RubySequencer的定义：

class RubySequencer(RubyPort):type = "RubySequencer"cxx_class = "gem5::ruby::Sequencer"cxx_header = "mem/ruby/system/Sequencer.hh"

RubySequencer 不是Sequencer： python与c++的关系。

细看会发现，我们用的是 RubySequencer 不是Sequencer ，RubySequencer是python的class,他的type是cpp里的"gem5::ruby::Sequencer"。还告诉我们用的头文件是 “mem/ruby/system/Sequencer.hh”。

cpp Sequencer.hh 没有

先看src/mem/ruby/system/Sequencer.hh 中，

class Sequencer : public RubyPort

所以Sequencer 其实是继承自RubyPort的。而RubyPort继承自clockedobject.
这俩都没有.slave 子成员。那我们的python代码调用的slave来自于哪里？

RubyPort的python定义

对rubyport最关键的代码出现了：src/mem/ruby/system/Sequencer.py
没错，竟然没有一个单独的python文件 RubyPort.py 而是在 Sequencer.py里。
step1 这个代码把c++和python联系起来了。
step2 这个代码创建了新的python里的名字

in_port同时也是弃用的slave
interrupt_out_port同时也是弃用的master
pio_request_port同时也是弃用的 pio_master_port
mem_request_port 同时也是弃用的mem_master_port
pio_response_port 同时也是弃用的pio_slave_port

class RubyPort(ClockedObject):type = "RubyPort"abstract = Truecxx_header = "mem/ruby/system/RubyPort.hh"cxx_class = "gem5::ruby::RubyPort"version = Param.Int(0, "")in_ports = VectorResponsePort("CPU side of this RubyPort/Sequencer. ""The CPU request ports should be connected to this. If a CPU ""has multiple ports (e.g., I/D ports) all of the ports for a ""single CPU can connect to one RubyPort.")slave = DeprecatedParam(in_ports, "`slave` is now called `in_ports`")interrupt_out_port = VectorRequestPort("Port to connect to x86 interrupt ""controller to send the CPU requests from outside.")master = DeprecatedParam(interrupt_out_port, "`master` is now called `interrupt_out_port`")pio_request_port = RequestPort("Ruby pio request port")pio_master_port = DeprecatedParam(pio_request_port, "`pio_master_port` is now called `pio_request_port`")mem_request_port = RequestPort("Ruby mem request port")mem_master_port = DeprecatedParam(mem_request_port, "`mem_master_port` is now called `mem_request_port`")pio_response_port = ResponsePort("Ruby pio response port")pio_slave_port = DeprecatedParam(pio_response_port, "`pio_slave_port` is now called `pio_response_port`")

这些python的port和 c++port的定义

是python提供字符串描述，然后调用python通过名字找port的函数，然后cpp响应这个函数，返回对应的cpp对象。由此，python定义的port和c++的port联系起来。
下面是细节，分别是根据名字字符串找port 的函数， c++对port名字的回应，和这些port的对应关系。

根据名字字符串找port 的函数

在src/python/m5/params.py中

class RequestPort(Port):# RequestPort("description")def __init__(self, desc):super().__init__("GEM5 REQUESTOR", desc, is_source=True)

c++对port名字的回应

Port &
RubyPort::getPort(const std::string &if_name, PortID idx)
{if (if_name == "mem_request_port") {return memRequestPort;} else if (if_name == "pio_request_port") {return pioRequestPort;} else if (if_name == "mem_response_port") {return memResponsePort;} else if (if_name == "pio_response_port") {return pioResponsePort;} else if (if_name == "interrupt_out_port") {// used by the x86 CPUs to connect the interrupt PIO and interrupt// response portif (idx >= static_cast<PortID>(request_ports.size())) {panic("%s: unknown %s index (%d)\n", __func__, if_name, idx);}return *request_ports[idx];} else if (if_name == "in_ports") {// used by the CPUs to connect the caches to the interconnect, and// for the x86 case also the interrupt request portif (idx >= static_cast<PortID>(response_ports.size())) {panic("%s: unknown %s index (%d)\n", __func__, if_name, idx);}return *response_ports[idx];}// pass it along to our super classreturn ClockedObject::getPort(if_name, idx);
}

python port和 cpp port的对应关系：根据name返回

mem_request_port 和 memRequestPort

python 文件中，mem_request_port 是来自于 RequestPort(“Ruby mem request port”)
mem_request_port = RequestPort(“Ruby mem request port”)
查找返回的是 if (if_name == “mem_request_port”) { return memRequestPort;

pio_request_port和 pioRequestPort

python 文件中， pio_request_port = RequestPort(“Ruby pio request port”)
查找的cpp返回的是 else if (if_name == “pio_request_port”) { return pioRequestPort;

pio_response_port 和 pioResponsePort

python 文件中 pio_response_port = ResponsePort(“Ruby pio response port”)
查找的cpp返回的是 else if (if_name == “pio_response_port”) { return pioResponsePort;

interrupt_out_port 和*request_ports[idx]

python 文件中 pio_response_port = ResponsePort(“Ruby pio response port”)
查找的cpp返回的是 else if (if_name == “interrupt_out_port”) { // used by the x86 CPUs to connect the interrupt PIO and interrupt // response port if (idx >= static_cast(request_ports.size())) { panic(“%s: unknown %s index (%d)\n”, func, if_name, idx); }

in_ports 和 *response_ports[idx]

python 文件中 in_ports = VectorResponsePort( "CPU side of this RubyPort/Sequencer. " “The CPU request ports should be connected to this. If a CPU " “has multiple ports (e.g., I/D ports) all of the ports for a " “single CPU can connect to one RubyPort.” )
查找的cpp返回的是 else if (if_name == “in_ports”) { // used by the CPUs to connect the caches to the interconnect, and // for the x86 case also the interrupt request port if (idx >= static_cast(response_ports.size())) { panic(”%s: unknown %s index (%d)\n”, func, if_name, idx); } return *response_ports[idx];

这些python port（同时也代表c++port）怎么连接的

核心是这些连接是由python文件定义，我们还是以 simple-MI_example.py为例子：

cpu和sequencer

# Connect the cpu's cache, interrupt, and TLB ports to Rubyfor i,cpu in enumerate(cpus):cpu.icache_port = self.sequencers[i].slavecpu.dcache_port = self.sequencers[i].slaveisa = buildEnv['TARGET_ISA']if isa == 'x86':cpu.interrupts[0].pio = self.sequencers[i].mastercpu.interrupts[0].int_master = self.sequencers[i].slavecpu.interrupts[0].int_slave = self.sequencers[i].masterif isa == 'x86' or isa == 'arm':cpu.itb.walker.port = self.sequencers[i].slavecpu.dtb.walker.port = self.sequencers[i].slave

cpu 与sequencer 的连接图

画成图就是
在这里插入图片描述

network 和 l1 dir

l1 连接l1的port和network

def connectQueues(self, ruby_system):"""Connect all of the queues for this controller."""self.mandatoryQueue = MessageBuffer()self.requestFromCache = MessageBuffer(ordered = True)self.requestFromCache.master = ruby_system.network.slaveself.responseFromCache = MessageBuffer(ordered = True)self.responseFromCache.master = ruby_system.network.slaveself.forwardToCache = MessageBuffer(ordered = True)self.forwardToCache.slave = ruby_system.network.masterself.responseToCache = MessageBuffer(ordered = True)self.responseToCache.slave = ruby_system.network.master

DirController 里，连接dir 的port和network

def connectQueues(self, ruby_system):self.requestToDir = MessageBuffer(ordered = True)self.requestToDir.slave = ruby_system.network.masterself.dmaRequestToDir = MessageBuffer(ordered = True)self.dmaRequestToDir.slave = ruby_system.network.masterself.responseFromDir = MessageBuffer()self.responseFromDir.master = ruby_system.network.slaveself.dmaResponseFromDir = MessageBuffer(ordered = True)self.dmaResponseFromDir.master = ruby_system.network.slaveself.forwardFromDir = MessageBuffer()self.forwardFromDir.master = ruby_system.network.slaveself.responseFromMemory = MessageBuffer()
## network 里，连接router和 l1以及dir
```pythonself.ext_links = [SimpleExtLink(link_id=i, ext_node=c,int_node=self.routers[i])for i, c in enumerate(controllers)]

network 里连接network.router 和conrollers

# Make a link from each controller to the router. The link goes# externally to the network.self.ext_links = [SimpleExtLink(link_id=i, ext_node=c,int_node=self.routers[i])for i, c in enumerate(controllers)]

network with routers 与l1， dir 的连接图

画成图就是
在这里插入图片描述
#小结
再把sequencer中的cacher和l1相连起来就全部串起来了
最后的总结图：

简介