This patch does a bunch of house-keeping updates on the DMA, including
indentation, and formatting, but most importantly breaks out the
response handling such that it can be shared between the atomic and
timing modes. It also removes a potential bug caused by the atomic
handling of responses only deleting the allocated request (pkt->req)
once the DMA action completes instead of doing so for every packet.
Before this patch, the handling of responses was near identical for
atomic and timing, but the code was simply duplicated. With this
patch, the handleResp method deals with the responses in both cases.
There are further updates to make after removing the NACKs, but that
will be part of a separate follow-up patch. This patch does not change
the behaviour of any regression.
This patch removes the NACK frrom the packet as there is no longer any
module in the system that issues them (the bridge was the only one and
the previous patch removes that).
The handling of NACKs was mostly avoided throughout the code base, by
using e.g. panic or assert false, but in a few locations the NACKs
were actually dealt with (although NACKs never occured in any of the
regressions). Most notably, the DMA port will now never receive a NACK
and the backoff time is thus never changed. As a consequence, the
entire backoff mechanism (similar to a PCI bus) is now removed and the
DMA port entirely relies on the bus performing the arbitration and
issuing a retry when appropriate. This is more in line with e.g. PCIe.
Surprisingly, this patch has no impact on any of the regressions. As
mentioned in the patch that removes the NACK from the bridge, a
follow-up patch should change the request and response buffer size for
at least one regression to also verify that the system behaves as
expected when the bridge fills up.
This patch removes the NACKing in the bridge, as the split
request/response busses now ensure that protocol deadlocks do not
occur, i.e. the message-dependency chain is broken by always allowing
responses to make progress without being stalled by requests. The
NACKs had limited support in the system with most components ignoring
their use (with a suitable call to panic), and as the NACKs are no
longer needed to avoid protocol deadlocks, the cleanest way is to
simply remove them.
The bridge is the starting point as this is the only place where the
NACKs are created. A follow-up patch will remove the code that deals
with NACKs in the endpoints, e.g. the X86 table walker and DMA
port. Ultimately the type of packet can be complete removed (until
someone sees a need for modelling more complex protocols, which can
now be done in parts of the system since the port and interface is
split).
As a consequence of the NACK removal, the bridge now has to send a
retry to a master if the request or response queue was full on the
first attempt. This change also makes the bridge ports very similar to
QueuedPorts, and a later patch will change the bridge to use these. A
first step in this direction is taken by aligning the name of the
member functions, as done by this patch.
A bit of tidying up has also been done as part of the simplifications.
Surprisingly, this patch has no impact on any of the
regressions. Hence, there was never any NACKs issued. In a follow-up
patch I would suggest changing the size of the bridge buffers set in
FSConfig.py to also test the situation where the bridge fills up.
This patch extends the queued port interfaces with methods for
scheduling the transmission of a timing request/response. The methods
are named similar to the corresponding sendTiming(Snoop)Req/Resp,
replacing the "send" with "sched". As the queues are currently
unbounded, the methods always succeed and hence do not return a value.
This functionality was previously provided in the subclasses by
calling PacketQueue::schedSendTiming with the appropriate
parameters. With this change, there is no need to introduce these
extra methods in the subclasses, and the use of the queued interface
is more uniform and explicit.
This patch removes the overloading of the parameter, which seems both
redundant, and possibly incorrect.
The PciConfigAll now also uses a Param.Latency rather than a
Param.Tick. For backwards compatibility it still sets the pio_latency
to 1 tick. All the comments have also been updated to not state that
it is in simticks when it is not necessarily the case.
This patch removes the overloading of the parameter, which seems both
redundant, and possibly incorrect.
The inorder CPU is particularly interesting as it uses a different
name for the parameter, and never make any use of it internally.
This patch allows packets to be enqueued in the same tick as they are
intended to be sent. This does not imply they actually are sent that
tick, although that is possible.
This change is useful for module that use the queued ports primarly to
avoid handling the flow control involved in sending and retrying
packets.
This patch tidies up the EventManager constructor and prunes a corner
case where the EventManager would initialise its eventq pointer to
NULL. This would cause segmentation faults on actual use and should
never happen.
This patch makes the Tick unsigned and removes the UTick typedef. The
ticks should never be negative, and there was only one major issue
with removing it, caused by the o3 CPU using a -1 as an initial value.
The patch has no impact on any regressions.
This patch moves the clock of the CPU, bus, and numerous devices to
the new class ClockedObject, that sits in between the SimObject and
MemObject in the class hierarchy. Although there are currently a fair
amount of MemObjects that do not make use of the clock, they
potentially should do so, e.g. the caches should at some point have
the same clock as the CPU, potentially with a 1:n ratio. This patch
does not introduce any new clock objects or object hierarchies
(clusters, clock domains etc), but is still a step in the direction of
having a more structured approach clock domains.
The most contentious part of this patch is the serialisation of clocks
that some of the modules (but not all) did previously. This
serialisation should not be needed as the clock is set through the
parameters even when restoring from the checkpoint. In other words,
the state is "stored" in the Python code that creates the modules.
The nextCycle methods are also simplified and the clock phase
parameter of the CPU is removed (this could be part of a clock object
once they are introduced).
This patch fixes the checkpointing by ensuring that the directory is
passer to the scriptCheckpoints function, and that the num_checkpoints
is not used before it is initialised.
Alpha System was overriding loadState() function to setup some functional
event. The system tried to read/write to memory before the Ruby memory had
unserialized the state. With this patch, Alpha System overrides the
startup() function, and sets up functional events in this function. This
works because startup() is called after Ruby memory system has unserialized
the memory state.
This patch fixes some problems with the drain/switchout functionality
for the O3 cpu and for the ARM ISA and adds some useful debug print
statements.
This is an incremental fix as there are still a few bugs/mem leaks with the
switchout code. Particularly when switching from an O3CPU to a
TimingSimpleCPU. However, when switching from O3 to O3 cores with the ARM ISA
I haven't encountered any more assertion failures; now the kernel will
typically panic inside of simulation.
This patch adds a --repeat-switch option that will enable repeat core
switching at a user defined period (set with --switch-freq option).
currently, a switch can only occur between like CPU types. inorder CPU
switching is not supported.
*note*
this patch simply allows a config that will perform repeat switching, it
does not fix drain/switchout functionality. if you run with repeat switching
you will hit assertion failures and/or your workload with hang or die.
New tool chains seem to be looking for kernel versions newer than what
this this was previously set to. Also take this opportunity to change
the hostname we report in uname to sim.gem5.org.
This patch moves instantiateTopology into Ruby.py and removes the
mem/ruby/network/topologies directory. It also adds some extra inheritance to
the topologies to clean up some issues in the existing topologies.
Off-by-one loop termination meant that we were stuffing
the terminating '\0' into the std::string value, which
makes for difficult-to-debug string comparison failures.
This replaces a (potentially uninitialized) string
field with a virtual function so that we can have
a safe interface without requiring changes to the
eio code.
Enable different whitelists for different OS/arch combinations,
since some use the generic Linux definitions only, and others
use definitions inherited from earlier Unix flavors on those
architectures.
Also update x86 function pointers so ioctl is no longer
unimplemented on that platform.
This patch is a revised version of Vince Weaver's earlier patch.
This patch moves the code related to checkpointing from the run() function to
several different functions. The aim is to make the code more manageable. No
functionality changes are expected, but since the code is kind of unruly, it
is possible that some change might have creeped in.
This changes the way in which the cpu class while restoring from a checkpoint
is set. Earlier it was assumed if cpu type with which to restore is not same
as the cpu type with the which to run the simulation, then the checkpoint
should be restored with the atomic cpu. This assumption is being dropped. The
checkpoint can now be restored with any cpu type, the default being atomic cpu.
when using the checker i ran into problems where an instruction reading the
cpu id register failed because the ids did not match, and hence, the result
of the instruction did not match. this patch ensures that the ids match so
this instruction does not fail. this problem only seemed to manifest itself
when multiple cores were in the system, either multi-core, or extra switched-
out cores present in the system.
removes the optimization that forwards an exclusive copy to a requester on a
read, only for the i-cache. this optimization isn't necessary because we
typically won't be writing to the i-cache.
According to the A15 TRM the value of this register is as follows (assuming 16 word = 64 byte lines)
[31:29] Format - b100 specifies v7
[28] RAZ - b0
[27:24] CWG log2(max writeback size #words) - 0x4 16 words
[23:20] ERG log2(max reservation size #words) - 0x4 16 words
[19:16] DminLine log2(smallest dcache line #words) - 0x4 16 words
[15:14] L1Ip L1 index/tagging policy - b11 specifies PIPT
[13:4] RAZ - b0000000000
[3:0] IminLine log2(smallest icache line #words) - 0x4 16 words
This patch changes the se and fs script to use the clock option and
not simply set the CPUs clock to 2 GHz. It also makes a minor change
to the assignment of the switch_cpus clock to allow different clocks.
This patch changes the simple memory to have a single slave port
rather than a vector port. The simple memory makes no attempts at
modelling the contention between multiple ports, and any such
multiplexing and demultiplexing could be done in a bus (or crossbar)
outside the memory controller. This scenario also matches with the
ongoing work on a SimpleDRAM model, which will be a single-ported
single-channel controller that can be used in conjunction with a bus
(or crossbar) to create a multi-port multi-channel controller.
There are only very few regressions that make use of the vector port,
and these are all for functional accesses only. To facilitate these
cases, memtest and memtest-ruby have been updated to also have a
"functional" bus to perform the (de)multiplexing of the functional
memory accesses.
This patch adds the LIBRARY_PATH from the users OS environment to
Scons build environment. This path is used when linking to search for
libraries, and this patch enables tcmalloc to be used during the build
even if it is not placed in the default search paths.
