This patch simplifies the packet by removing the broadcast flag and
instead more firmly relying on (and enforcing) the semantics of
transactions in the classic memory system, i.e. request packets are
routed from a master to a slave based on the address, and when they
are created they have neither a valid source, nor destination. On
their way to the slave, the request packet is updated with a source
field for all modules that multiplex packets from multiple master
(e.g. a bus). When a request packet is turned into a response packet
(at the final slave), it moves the potentially populated source field
to the destination field, and the response packet is routed through
any multiplexing components back to the master based on the
destination field.
Modules that connect multiplexing components, such as caches and
bridges store any existing source and destination field in the sender
state as a stack (just as before).
The packet constructor is simplified in that there is no longer a need
to pass the Packet::Broadcast as the destination (this was always the
case for the classic memory system). In the case of Ruby, rather than
using the parameter to the constructor we now rely on setDest, as
there is already another three-argument constructor in the packet
class.
In many places where the packet information was printed as part of
DPRINTFs, request packets would be printed with a numeric "dest" that
would always be -1 (Broadcast) and that field is now removed from the
printing.
This patch introduces port access methods that separates snoop
request/responses from normal memory request/responses. The
differentiation is made for functional, atomic and timing accesses and
builds on the introduction of master and slave ports.
Before the introduction of this patch, the packets belonging to the
different phases of the protocol (request -> [forwarded snoop request
-> snoop response]* -> response) all use the same port access
functions, even though the snoop packets flow in the opposite
direction to the normal packet. That is, a coherent master sends
normal request and receives responses, but receives snoop requests and
sends snoop responses (vice versa for the slave). These two distinct
phases now use different access functions, as described below.
Starting with the functional access, a master sends a request to a
slave through sendFunctional, and the request packet is turned into a
response before the call returns. In a system without cache coherence,
this is all that is needed from the functional interface. For the
cache-coherent scenario, a slave also sends snoop requests to coherent
masters through sendFunctionalSnoop, with responses returned within
the same packet pointer. This is currently used by the bus and caches,
and the LSQ of the O3 CPU. The send/recvFunctional and
send/recvFunctionalSnoop are moved from the Port super class to the
appropriate subclass.
Atomic accesses follow the same flow as functional accesses, with
request being sent from master to slave through sendAtomic. In the
case of cache-coherent ports, a slave can send snoop requests to a
master through sendAtomicSnoop. Just as for the functional access
methods, the atomic send and receive member functions are moved to the
appropriate subclasses.
The timing access methods are different from the functional and atomic
in that requests and responses are separated in time and
send/recvTiming are used for both directions. Hence, a master uses
sendTiming to send a request to a slave, and a slave uses sendTiming
to send a response back to a master, at a later point in time. Snoop
requests and responses travel in the opposite direction, similar to
what happens in functional and atomic accesses. With the introduction
of this patch, it is possible to determine the direction of packets in
the bus, and no longer necessary to look for both a master and a slave
port with the requested port id.
In contrast to the normal recvFunctional, recvAtomic and recvTiming
that are pure virtual functions, the recvFunctionalSnoop,
recvAtomicSnoop and recvTimingSnoop have a default implementation that
calls panic. This is to allow non-coherent master and slave ports to
not implement these functions.
This patch introduces the notion of a master and slave port in the C++
code, thus bringing the previous classification from the Python
classes into the corresponding simulation objects and memory objects.
The patch enables us to classify behaviours into the two bins and add
assumptions and enfore compliance, also simplifying the two
interfaces. As a starting point, isSnooping is confined to a master
port, and getAddrRanges to slave ports. More of these specilisations
are to come in later patches.
The getPort function is not getMasterPort and getSlavePort, and
returns a port reference rather than a pointer as NULL would never be
a valid return value. The default implementation of these two
functions is placed in MemObject, and calls fatal.
The one drawback with this specific patch is that it requires some
code duplication, e.g. QueuedPort becomes QueuedMasterPort and
QueuedSlavePort, and BusPort becomes BusMasterPort and BusSlavePort
(avoiding multiple inheritance). With the later introduction of the
port interfaces, moving the functionality outside the port itself, a
lot of the duplicated code will disappear again.
This patch moves all port creation from the getPort method to be
consistently done in the MemObject's constructor. This is possible
thanks to the Swig interface passing the length of the vector ports.
Previously there was a mix of: 1) creating the ports as members (at
object construction time) and using getPort for the name resolution,
or 2) dynamically creating the ports in the getPort call. This is now
uniform. Furthermore, objects that would not be complete without a
port have these ports as members rather than having pointers to
dynamically allocated ports.
This patch also enables an elaboration-time enumeration of all the
ports in the system which can be used to determine the masterId.
This patch makes the bus bridge uni-directional and specialises the
bus ports to be a master port and a slave port. This greatly
simplifies the assumptions on both sides as either port only has to
deal with requests or responses. The following patches introduce the
notion of master and slave ports, and would not be possible without
this split of responsibilities.
In making the bridge unidirectional, the address range mechanism of
the bridge is also changed. For the cases where communication is
taking place both ways, an additional bridge is needed. This causes
issues with the existing mechanism, as the busses cannot determine
when to stop iterating the address updates from the two bridges. To
avoid this issue, and also greatly simplify the specification, the
bridge now has a fixed set of address ranges, specified at creation
time.
This patch simplifies the address-range determination mechanism and
also unifies the naming across ports and devices. It further splits
the queries for determining if a port is snooping and what address
ranges it responds to (aiming towards a separation of
cache-maintenance ports and pure memory-mapped ports). Default
behaviours are such that most ports do not have to define isSnooping,
and master ports need not implement getAddrRanges.
creation and initialization now happens in python. Parameter objects
are generated and initialized by python. The .ini file is now solely for
debugging purposes and is not used in construction of the objects in any
way.
--HG--
extra : convert_revision : 7e722873e417cb3d696f2e34c35ff488b7bff4ed
cache blocks that get dmaed ARE NOT marked invalid in the caches so it's a performance issue here
src/mem/bridge.cc:
src/mem/bridge.hh:
hopefully the final hacky change to make the bus bridge work ok
--HG--
extra : convert_revision : 62cbc65c74d1a84199f0a376546ec19994c5899c
src/dev/io_device.cc:
extra printing and assertions
src/mem/bridge.hh:
deal with packets only satisfying part of a request by making many requests
src/mem/cache/cache_impl.hh:
make the cache try to satisfy a functional request from the cache above it before checking itself
--HG--
extra : convert_revision : 1df52ab61d7967e14cc377c560495430a6af266a
add seperate response buffers and request queue sizes in bus bridge
add delay to respond to a nack in the bus bridge
src/dev/i8254xGBe.cc:
src/dev/ide_ctrl.cc:
src/dev/ns_gige.cc:
src/dev/pcidev.hh:
src/dev/sinic.cc:
add backoff delay parameters
src/dev/io_device.cc:
src/dev/io_device.hh:
add a backoff algorithm when nacks are received.
src/mem/bridge.cc:
src/mem/bridge.hh:
add seperate response buffers and request queue sizes
add a new parameters to specify how long before a nack in ready to go after a packet that needs to be nacked is received
src/mem/cache/cache_impl.hh:
assert on the
src/mem/tport.cc:
add a friendly assert to make sure the packet was inserted into the list
--HG--
extra : convert_revision : 3595ad932015a4ce2bb72772da7850ad91bd09b1
fix the timing cpu to handle receiving a nacked packet
src/cpu/simple/timing.cc:
make the timing cpu handle receiving a nacked packet
src/mem/bridge.cc:
src/mem/bridge.hh:
the bridge never returns false when recvTiming() is called on its ports now, it always returns true and nacks the packet if there isn't sufficient buffer space
--HG--
extra : convert_revision : 5e12d0cf6ce985a5f72bcb7ce26c83a76c34c50a
figure out the block size from devices attached to the bus otherwise use a default block size when no devices that care are attached
configs/common/FSConfig.py:
src/mem/bridge.cc:
src/mem/bridge.hh:
src/python/m5/objects/Bridge.py:
fix partial writes with a functional memory hack
src/mem/bus.cc:
src/mem/bus.hh:
src/python/m5/objects/Bus.py:
figure out the block size from devices attached to the bus otherwise use a default block size when no devices that care are attached
src/mem/packet.cc:
fix WriteInvalidateResp to not be a request that needs a response since it isn't
src/mem/port.hh:
by default return 0 for deviceBlockSize instead of panicing. This makes finding the block size the bus should use easier
--HG--
extra : convert_revision : 3fcfe95f9f392ef76f324ee8bd1d7f6de95c1a64
into Python.
Add Port and VectorPort objects and support for
specifying port connections via assignment.
The whole C++ ConfigNode hierarchy is gone now, as are
C++ Connector objects.
configs/test/fs.py:
configs/test/test.py:
Rewrite for new port connector syntax.
src/SConscript:
Remove unneeded files:
- mem/connector.*
- sim/config*
src/dev/io_device.hh:
src/mem/bridge.cc:
src/mem/bridge.hh:
src/mem/bus.cc:
src/mem/bus.hh:
src/mem/mem_object.hh:
src/mem/physical.cc:
src/mem/physical.hh:
Allow getPort() to take an optional index to
support vector ports (eventually).
src/python/m5/__init__.py:
Move SimObject construction and port connection
operations into Python (with C++ calls).
src/python/m5/config.py:
Move SimObject construction and port connection
operations into Python (with C++ calls).
Add support for declaring and connecting MemObject
ports in Python.
src/python/m5/objects/Bus.py:
src/python/m5/objects/PhysicalMemory.py:
Add port declaration.
src/sim/builder.cc:
src/sim/builder.hh:
src/sim/serialize.cc:
src/sim/serialize.hh:
ConfigNodes are gone; builder just gets the
name of a .ini file section now.
src/sim/main.cc:
Move SimObject construction and port connection
operations into Python (with C++ calls).
Split remaining initialization operations into two parts,
loadIniFile() and finalInit().
src/sim/param.cc:
src/sim/param.hh:
SimObject resolution done globally in Python now
(not via ConfigNode hierarchy).
src/sim/sim_object.cc:
Remove unneeded #include.
--HG--
extra : convert_revision : 2fa4001eaaec0c9a4231ef6e854f8e156d930dfe
it ends up being O(N^2). But it's probably going to have to change for the real bus anyway, so it should be rewritten then
Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
Removed Port Blocked/Unblocked and replaced with sendRetry().
Remove possibility of packet mangling if packet is going to be refused anyway in bridge
src/cpu/simple/atomic.cc:
src/cpu/simple/atomic.hh:
src/cpu/simple/timing.cc:
src/cpu/simple/timing.hh:
Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
src/dev/io_device.cc:
src/dev/io_device.hh:
Make DMA Timing requests/responses work.
Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
src/mem/bridge.cc:
src/mem/bridge.hh:
Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
Removed Port Blocked/Unblocked and replaced with sendRetry().
Remove posibility of packet mangling if packet is going to be refused anyway.
src/mem/bus.cc:
src/mem/bus.hh:
Add a very poor implementation of dealing with retries on timing requests. It is especially slow with tracing on since
it ends up being O(N^2). But it's probably going to have to change for the real bus anyway, so it should be rewritten then
src/mem/port.hh:
Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
Removed Blocked/Unblocked port status, their functionality is really duplicated in the recvRetry() method
--HG--
extra : convert_revision : fab613404be54bfa7a4c67572bae7b559169e573
Store original source & senderState for timing packets
that get a response, so we can properly route the
response packet back to the original sender.
--HG--
extra : convert_revision : 03dbcc8dc06d93de243bfcdc3cbaa012773c6782