This patch uses the recently added XOR hashing capabilities for the
DRAM channel interleaving. This avoids channel biasing due to strided
access patterns.
This patch changes the DRAM channel interleaving default behaviour to
be more representative. The default address mapping (RoRaBaCoCh) moves
the channel bits towards the least significant bits, and uses 128 byte
as the default channel interleaving granularity.
These defaults can be overridden if desired, but should serve as a
sensible starting point for most use-cases.
Fix the makeArmSystem routine to reflect recent changes that support kernel
commandline option when running android. Without this fix, trying to run
android encounters a 'reference before assignment' error.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
DMA Controller was not being connected to the network for the MESI_Three_Level
protocol as was being done in the other protocol config files. Without this
patch, this protocol segfaults during startup.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
when trying to dual boot on arm build_drive_system will only use the default
values for the dtb file, number of processors, and disk image. if you are using
the non-default files by passing values on the command line for example, or by
making a new entry in Benchmarks.py, the build config scripts will still look
for the default files. this will lead to the wrong system files being used, or
the simulator will fail if you do not have them.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch gives the user direct influence over the number of DRAM
ranks to make it easier to tune the memory density without affecting
the bandwidth (previously the only means of scaling the device count
was through the number of channels).
The patch also adds some basic sanity checks to ensure that the number
of ranks is a power of two (since we rely on bit slices in the address
decoding).
This patch adds the --memchecker option, to denote that a MemChecker
should be instantiated for the system. The exact usage of the MemChecker
depends on the system configuration.
For now CacheConfig.py makes use of the option, adding MemCheckerMonitor
instances between CPUs and D-Caches.
Note, however, that currently this only provides limited checking on a
running system; other parts of the system, such as I/O devices are not
monitored, and may cause warnings to be issued by the monitor.
More documentation at http://gem5.org/Simpoints
Steps to profile, generate, and use SimPoints with gem5:
1. To profile workload and generate SimPoint BBV file, use the
following option:
--simpoint-profile --simpoint-interval <interval length>
Requires single Atomic CPU and fastmem.
<interval length> is in number of instructions.
2. Generate SimPoint analysis using SimPoint 3.2 from UCSD.
(SimPoint 3.2 not included with this flow.)
3. To take gem5 checkpoints based on SimPoint analysis, use the
following option:
--take-simpoint-checkpoint=<simpoint file path>,<weight file
path>,<interval length>,<warmup length>
<simpoint file> and <weight file> is generated by SimPoint analysis
tool from UCSD. SimPoint 3.2 format expected. <interval length> and
<warmup length> are in number of instructions.
4. To resume from gem5 SimPoint checkpoints, use the following option:
--restore-simpoint-checkpoint -r <N> --checkpoint-dir <simpoint
checkpoint path>
<N> is (SimPoint index + 1). E.g., "-r 1" will resume from SimPoint
#0.
Both options accept template which will, through python string formatting,
have "mem", "disk", and "script" values substituted in from the mdesc.
Additional values can be used on a case by case basis by passing them as
keyword arguments to the fillInCmdLine function. That makes it possible to
have specialized parameters for a particular ISA, for instance.
The first option lets you specify the template directly, and the other lets
you specify a file which has the template in it.
In fs.py the io port controller was being attached to the iobus multiple
times. This should be done only once. In se.py, the the option use_map
was being set which no longer exists.
Mwait works as follows:
1. A cpu monitors an address of interest (monitor instruction)
2. A cpu calls mwait - this loads the cache line into that cpu's cache.
3. The cpu goes to sleep.
4. When another processor requests write permission for the line, it is
evicted from the sleeping cpu's cache. This eviction is forwarded to the
sleeping cpu, which then wakes up.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
Ruby's functional accesses are not guaranteed to succeed as of now. While
this is not a problem for the protocols that are currently in the mainline
repo, it seems that coherence protocols for gpus rely on a backing store to
supply the correct data. The aim of this patch is to make this backing store
configurable i.e. it comes into play only when a particular option:
--access-backing-store is invoked.
The backing store has been there since M5 and GEMS were integrated. The only
difference is that earlier the system used to maintain the backing store and
ruby's copy was write-only. Sometime last year, we moved to data being
supplied supplied by ruby in SE mode simulations. And now we have patches on
the reviewboard, which remove ruby's copy of memory altogether and rely
completely on the system's memory to supply data. This patch adds back a
SimpleMemory member to RubySystem. This member is used only if the option:
access-backing-store is set to true. By default, the memory would not be
accessed.
This patch is the final in the series. The whole series and this patch in
particular were written with the aim of interfacing ruby's directory controller
with the memory controller in the classic memory system. This is being done
since ruby's memory controller has not being kept up to date with the changes
going on in DRAMs. Classic's memory controller is more up to date and
supports multiple different types of DRAM. This also brings classic and
ruby ever more close. The patch also changes ruby's memory controller to
expose the same interface.
Both ruby and the system used to maintain memory copies. With the changes
carried for programmed io accesses, only one single memory is required for
fs simulations. This patch sets the copy of memory that used to reside
with the system to null, so that no space is allocated, but address checks
can still be carried out. All the memory accesses now source and sink values
to the memory maintained by ruby.
This changes the default ARM system to a Versatile Express-like system that supports
2GB of memory and PCI devices and updates the default kernels/file-systems for
AArch64 ARM systems (64-bit) to support up to 32GB of memory and PCI devices. Some
platforms that are no longer supported have been pruned from the configuration files.
In addition a set of 64-bit ARM regressions have been added to the regression system.
The bare-metal configuration option still configured memory with the old scheme
that no-longer works. This change unifies the code so there aren't any differences.
This patch adds the ability to load in config.ini files generated from
gem5 into another instance of gem5 built without Python configuration
support. The intended use case is for configuring gem5 when it is a
library embedded in another simulation system.
A parallel config file reader is also provided purely in Python to
demonstrate the approach taken and to provided similar functionality
for as-yet-unknown use models. The Python configuration file reader
can read both .ini and .json files.
C++ configuration file reading:
A command line option has been added for scons to enable C++ configuration
file reading: --with-cxx-config
There is an example in util/cxx_config that shows C++ configuration in action.
util/cxx_config/README explains how to build the example.
Configuration is achieved by the object CxxConfigManager. It handles
reading object descriptions from a CxxConfigFileBase object which
wraps a config file reader. The wrapper class CxxIniFile is provided
which wraps an IniFile for reading .ini files. Reading .json files
from C++ would be possible with a similar wrapper and a JSON parser.
After reading object descriptions, CxxConfigManager creates
SimObjectParam-derived objects from the classes in the (generated with this
patch) directory build/ARCH/cxx_config
CxxConfigManager can then build SimObjects from those SimObjectParams (in an
order dictated by the SimObject-value parameters on other objects) and bind
ports of the produced SimObjects.
A minimal set of instantiate-replacing member functions are provided by
CxxConfigManager and few of the member functions of SimObject (such as drain)
are extended onto CxxConfigManager.
Python configuration file reading (configs/example/read_config.py):
A Python version of the reader is also supplied with a similar interface to
CxxConfigFileBase (In Python: ConfigFile) to config file readers.
The Python config file reading will handle both .ini and .json files.
The object construction strategy is slightly different in Python from the C++
reader as you need to avoid objects prematurely becoming the children of other
objects when setting parameters.
Port binding also needs to be strictly in the same port-index order as the
original instantiation.
This patch moves code for instantiating a single memory controller from
the function config_mem() to a separate function. This is being done
so that memory controllers can be instantiated without assuming that
they will be attached to the system in a particular fashion.
This patch force IO device to be mapped to 0xC0000000-0xFFFF0000 by
reserve anything between the end of memory and 3GB if memory is less
than 3GB. It also statically bridge these address range to the IO bus,
which guaranty access to pci address space will pass though bridge to
iobus.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch assign bus_id=0 to PCI bus and bus_id=1 to ISA bus for
X86 platform. Because PCI device get config space address using
Pc::calcPciConfigAddr() which requires "assert(bus==0)".
This fixes PCI interrupt routing and discovery on Linux.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch changes the name of the Bus classes to XBar to better
reflect the actual timing behaviour. The actual instances in the
config scripts are not renamed, and remain as e.g. iobus or membus.
As part of this renaming, the code has also been clean up slightly,
making use of range-based for loops and tidying up some comments. The
only changes outside the bus/crossbar code is due to the delay
variables in the packet.
--HG--
rename : src/mem/Bus.py => src/mem/XBar.py
rename : src/mem/coherent_bus.cc => src/mem/coherent_xbar.cc
rename : src/mem/coherent_bus.hh => src/mem/coherent_xbar.hh
rename : src/mem/noncoherent_bus.cc => src/mem/noncoherent_xbar.cc
rename : src/mem/noncoherent_bus.hh => src/mem/noncoherent_xbar.hh
rename : src/mem/bus.cc => src/mem/xbar.cc
rename : src/mem/bus.hh => src/mem/xbar.hh
Add new DRAM_ROTATE mode to traffic generator.
This mode will generate DRAM traffic that rotates across
banks per rank, command types, and ranks per channel
The looping order is illustrated below:
for (ranks per channel)
for (command types)
for (banks per rank)
// Generate DRAM Command Series
This patch also adds the read percentage as an input argument to the
DRAM sweep script. If the simulated read percentage is 0 or 100, the
middle for loop does not generate additional commands. This loop is
used only when the read percentage is set to 50, in which case the
middle loop will toggle between read and write commands.
Modified sweep.py script, which generates DRAM traffic.
Added input arguments and support for new DRAM_ROTATE mode.
The script now has input arguments for:
1) Read percentage
2) Number of ranks
3) Address mapping
4) Traffic generator mode (DRAM or DRAM_ROTATE)
The default values are:
100% reads, 1 rank, RoRaBaCoCh address mapping, and DRAM traffic gen mode
For the DRAM traffic mode, added multi-rank support.
Change the default kernel for AArch64 and since it supports PCI devices
remove the hack that made it use CF. Unfortunately, there isn't really
a half-way here and we need to switch. Current users will get an error
message that the kernel isn't found and hopefully go download a new
kernel that supports PCI.
As highlighed on the mailing list gem5's writeback modeling can impact
performance. This patch removes the limitation on maximum outstanding issued
instructions, however the number that can writeback in a single cycle is still
respected in instToCommit().
This patch adds basic functionality to quickly visualise the output
from the DRAM efficiency script. There are some unfortunate hacks
needed to communicate the needed information from one script to the
other, and we fall back on (ab)using the simout to do this.
As part of this patch we also trim the efficiency sweep to stop at 512
bytes as this should be sufficient for all forseeable DRAMs.
This patch is the final patch in a series of patches. The aim of the series
is to make ruby more configurable than it was. More specifically, the
connections between controllers are not at all possible (unless one is ready
to make significant changes to the coherence protocol). Moreover the buffers
themselves are magically connected to the network inside the slicc code.
These connections are not part of the configuration file.
This patch makes changes so that these connections will now be made in the
python configuration files associated with the protocols. This requires
each state machine to expose the message buffers it uses for input and output.
So, the patch makes these buffers configurable members of the machines.
The patch drops the slicc code that usd to connect these buffers to the
network. Now these buffers are exposed to the python configuration system
as Master and Slave ports. In the configuration files, any master port
can be connected any slave port. The file pyobject.cc has been modified to
take care of allocating the actual message buffer. This is inline with how
other port connections work.
This patch fixes scripts related to ruby by adding the ruby clock domain.
Now the L1 controllers and the Sequencer shares the cpu clock domain,
while the rest of the components use the ruby clock domain.
Before this patch, running simulations with the cpu clock set at 2GHz or
1GHz will output the same time results and could distort power measurements.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
the Cortex-A15 has a random replacement policy for its L2 cache. see the
Cortex-A15 Technical Reference Manual 1.7 About the L2 memory system. this
patch makes the PseudoLRU tags the default for the ARM O3 CPU's L2 cache.
This patch contains a new CPU model named `Minor'. Minor models a four
stage in-order execution pipeline (fetch lines, decompose into
macroops, decompose macroops into microops, execute).
The model was developed to support the ARM ISA but should be fixable
to support all the remaining gem5 ISAs. It currently also works for
Alpha, and regressions are included for ARM and Alpha (including Linux
boot).
Documentation for the model can be found in src/doc/inside-minor.doxygen and
its internal operations can be visualised using the Minorview tool
utils/minorview.py.
Minor was designed to be fairly simple and not to engage in a lot of
instruction annotation. As such, it currently has very few gathered
stats and may lack other gem5 features.
Minor is faster than the o3 model. Sample results:
Benchmark | Stat host_seconds (s)
---------------+--------v--------v--------
(on ARM, opt) | simple | o3 | minor
| timing | timing | timing
---------------+--------+--------+--------
10.linux-boot | 169 | 1883 | 1075
10.mcf | 117 | 967 | 491
20.parser | 668 | 6315 | 3146
30.eon | 542 | 3413 | 2414
40.perlbmk | 2339 | 20905 | 11532
50.vortex | 122 | 1094 | 588
60.bzip2 | 2045 | 18061 | 9662
70.twolf | 207 | 2736 | 1036
in makeDualRoot() the etherlink interfaces are set using the tsunami interface
however, they are set again a few lines later based on whether or not the system
is a realview or tsunami system; the original assignment is always overwritten
or there will be a fatal. this seems like an artifact from when tsunami was the
only type of system capable of running with the dual option.
This patch bumps the bus clock speed such that the interconnect does
not become a bottleneck with a DDR4-2400-x64 DRAM delivering 19.2
GByte/s theoretical max.
Adds the parameter --num-work-ids to Options.py and reads the parameter
into the System params in Simulation.py. This parameter enables setting
the number of possible work items to different than 16. Support for this
parameter already exists in src/sim/System.py, so this changeset only
affects the Python config files.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
A recent changeset altered the default memory class to DRAMCtrl. In se mode,
ruby uses the physical memory to check if a given address is within the bounds
of the physical memory. SimpleMemory is enough for this. Moreover,
SimpleMemory does not check whether it is connected or not, something which
DRAMCtrl does.
This patch renames the not-so-simple SimpleDRAM to a more suitable
DRAMCtrl. The name change is intended to ensure that we do not send
the wrong message (although the "simple" in SimpleDRAM was originally
intended as in cleverly simple, or elegant).
As the DRAM controller modelling work is being presented at ISPASS'14
our hope is that a broader audience will use the model in the future.
--HG--
rename : src/mem/SimpleDRAM.py => src/mem/DRAMCtrl.py
rename : src/mem/simple_dram.cc => src/mem/dram_ctrl.cc
rename : src/mem/simple_dram.hh => src/mem/dram_ctrl.hh
Make the default memory type DDR3-1600 x64, and use the open-adaptive
page policy. This change is aiming to ensure that users by default are
using a realistic memory system.
This patch adds a configuration that simplifies evaluation of DRAM
controller configurations by automating a sweep of stride size and
bank parallelism. It works in a rather unconventional way, as it needs
to print the traffic generator stimuli based on the memory
organisation. Hence, it starts by configuring the memory, then it
prints a traffic-generator config file, and loads it.
The resulting stats have one period per data point, identified by the
stride size, and the number of banks being used.
This patch adds the row bits to the name of the address mapping
schemes to make it more clear that all the current schemes places the
row bits as the most significant bits.
This helps in configuring the network interfaces from the python script and
these objects no longer rely on the network object for the timing information.
The code that creates test and drive systems is being moved to separate
functions so as to make the code more readable. Ultimately the two
functions would be combined so that the replicated code is eliminated.
The patch removes the ruby_fs.py file. The functionality is being moved to
fs.py. This would being ruby fs simulations in line with how ruby se
simulations are started (using --ruby option). The alpha fs config functions
are being combined for classing and ruby memory systems. This required
renaming the piobus in ruby to iobus. So, we will have stats being renamed
in the stats file for ruby fs regression.
Piobus was recently added to se scripts for ruby so that the interrupt
controller can be connected to something (required since the interrupt
controller sends address range messages). This patch removes the piobus
and instead, the pio port of ruby port will now ignore the range change
messages in se mode.
Couple of errors were discovered in 4eec7bdde5b0 which necessitated this patch.
Firstly, we create interrupt controllers in the se mode, but no piobus was
being created. RubyPort, which earlier used to ignore range changes now
forwards those to the piobus. The lack of piobus resulted in segmentation
fault. This patch creates a piobus even in se mode. It is not created only
when some tester is running. Secondly, I had missed out on modifying port
connections for other coherence protocols.
Currently, the interrupt controller in x86 is connected to the io bus
directly. Therefore the packets between the io devices and the interrupt
controller do not go through ruby. This patch changes ruby port so that
these packets arrive at the ruby port first, which then routes them to their
destination. Note that the patch does not make these packets go through the
ruby network. That would happen in a subsequent patch.
Modifies FSConfig.py to enable ARMv8 compatibility.
To boot gem5 with ARMv8:
Download the v8 kernel, .dtb file, and root FS from: http://gem5.org/Download
Download the ARMv8 toolchain, and add the bin dir to your path:
http://www.linaro.org/engineering/engineering-projects/armv8
Build gem5 for ARM
Build the v8 bootloader (in gem5/system/arm/aarch64_bootloader)
Make script in gem5/system/arm/aarch64_bootloader will require v8 toolchain,
drop the produced boot_emm.arm64 in $(M5_PATH)/binaries/
Run:
$ build/ARM/gem5.fast configs/example/fs.py --machine-type=VExpress_EMM64 \
--kernel=/path/to/kernel/vmlinux-linaro-tracking \
--dtb-filename=/path/to/dtb/rtsm_ve-aemv8a.dtb \
--disk-image=/path/to/img/linaro-minimal-armv8.img
This patch adds DRAMSim2 as a memory controller by wrapping the
external library and creating a sublass of AbstractMemory that bridges
between the semantics of gem5 and the DRAMSim2 interface.
The DRAMSim2 wrapper extracts the clock period from the config
file. There is no way of extracting this information from DRAMSim2
itself, so we simply read the same config file and get it from there.
To properly model the response queue, the wrapper keeps track of how
many transactions are in the actual controller, and how many are
stacking up waiting to be sent back as responses (in the wrapper). The
latter requires us to move away from the queued port and manage the
packets ourselves. This is due to DRAMSim2 not having any flow control
on the response path.
DRAMSim2 assumes that the transactions it is given are matching the
burst size of the choosen memory. The wrapper checks to ensure the
cache line size of the system matches the burst size of DRAMSim2 as
there are currently no provisions to split the system requests. In
theory we could allow a cache line size smaller than the burst size,
but that would lead to inefficient use of the DRAM, so for not we
fatal also in this case.
Note: AArch64 and AArch32 interworking is not supported. If you use an AArch64
kernel you are restricted to AArch64 user-mode binaries. This will be addressed
in a later patch.
Note: Virtualization is only supported in AArch32 mode. This will also be fixed
in a later patch.
Contributors:
Giacomo Gabrielli (TrustZone, LPAE, system-level AArch64, AArch64 NEON, validation)
Thomas Grocutt (AArch32 Virtualization, AArch64 FP, validation)
Mbou Eyole (AArch64 NEON, validation)
Ali Saidi (AArch64 Linux support, code integration, validation)
Edmund Grimley-Evans (AArch64 FP)
William Wang (AArch64 Linux support)
Rene De Jong (AArch64 Linux support, performance opt.)
Matt Horsnell (AArch64 MP, validation)
Matt Evans (device models, code integration, validation)
Chris Adeniyi-Jones (AArch64 syscall-emulation)
Prakash Ramrakhyani (validation)
Dam Sunwoo (validation)
Chander Sudanthi (validation)
Stephan Diestelhorst (validation)
Andreas Hansson (code integration, performance opt.)
Eric Van Hensbergen (performance opt.)
Gabe Black
The first two levels (L0, L1) are private to the core, the third level (L2)is
possibly shared. The protocol supports clustered designs. For example, one
can have two sets of two cores. Each core has an L0 and L1 cache. There are
two L2 controllers where each set accesses only one of the L2 controllers.
For some reason, the default x86 kernel is specified in
tests/configs/x86_generic.py and not in configs/common/FSConfig.py,
where the kernels for all the other ISAs are. This means that
running configs/example/fs.py for x86 fails because no kernel
is specified. Moving the specification over fixes this problem.
There is another problem that this uncovers, which is that going
past the init stage (i.e., past where the regression test stops)
fails because the fsck test on the disk device fails, but that's
a separate issue.
The directory controller should not have the sharer field since there is
only one level 2 cache. Anyway the field was not in use. The owner field
was being used to track the l2 cache version (in case of distributed l2) that
has the cache block under consideration. The information is not required
since the version of the level 2 cache can be obtained from a subset of the
address bits.
the current implementation of the fetch buffer in the o3 cpu
is only allowed to be the size of a cache line. some
architectures, e.g., ARM, have fetch buffers smaller than a cache
line, see slide 22 at:
http://www.arm.com/files/pdf/at-exploring_the_design_of_the_cortex-a15.pdf
this patch allows the fetch buffer to be set to values smaller
than a cache line.
This Python script generates an ARM DS-5 Streamline .apc project based
on gem5 run. To successfully convert, the gem5 runs needs to be run
with the context-switch-based stats dump option enabled (The guest
kernel also needs to be patched to allow gem5 interrogate its task
information.) See help for more information.
A couple of recent changesets added/deleted/edited some variables
that are needed for running the example ruby scripts. This changeset
edits these scripts to bring them to a working state.
In order to support m5ops in virtualized environments, we need to use
a memory mapped interface. This changeset adds support for that by
reserving 0xFFFF0000-0xFFFFFFFF and mapping those to the generic IPR
interface for m5ops. The mapping is done in the
X86ISA::TLB::finalizePhysical() which means that it just works for all
of the CPU models, including virtualized ones.
Recent changes added setting of system-wide cache line size and these settings
occur in the top-level configs (se.py and fs.py). This setting also needs to
take place in ruby_fs.py. This change sets the cache line size as appropriate.
The previous changeset (9816) that fixes the use of max ticks introduced the
variable cpt_starttick, which is used for setting the relative max tick.
Unfortunately, with checkpointing at an instruction count or with simpoints,
the checkpoint tick is not stored conveniently, so to ensure that cpt_starttick
is initialized, set it to 0. Also, if using --rel-max-tick, check the use of
instruction counts or simpoints to warn the user that the max tick setting does
not include the checkpoint ticks.
The routers are created before the network class. This results in the routers
becoming children of the first link they are connected to and they get generic
names like int_node and node_b. This patch creates the network object first
and passes it to the topology creation function. Now the routers are children
of the network object and names are much more sensible.
The number of transitions per cycle that a controller can carry out is
a proxy for the number of ports that a controller has. This value is
currently 32 which is way too high. The patch introduces an option
for the number of ports and uses this option in the protocol files
to set the number of transitions. The default value is being set to
4. None of the se regressions change. Ruby stats for the fs regression
change and are being updated.
This patch adds support for specifying multi-channel memory
configurations on the command line, e.g. 'se/fs.py
--mem-type=ddr3_1600_x64 --mem-channels=4'. To enable this, it
enhances the functionality of MemConfig and moves the existing
makeMultiChannel class method from SimpleDRAM to the support scripts.
The se/fs.py example scripts are updated to make use of the new
feature.
This patch changes the default parameter value of conf_table_reported
to match the common case. It also simplifies the regression and config
scripts to reflect this change.
This patch adds the notion of voltage domains, and groups clock
domains that operate under the same voltage (i.e. power supply) into
domains. Each clock domain is required to be associated with a voltage
domain, and the latter requires the voltage to be explicitly set.
A voltage domain is an independently controllable voltage supply being
provided to section of the design. Thus, if you wish to perform
dynamic voltage scaling on a CPU, its clock domain should be
associated with a separate voltage domain.
The current implementation of the voltage domain does not take into
consideration cases where there are derived voltage domains running at
ratio of native voltage domains, as with the case where there can be
on-chip buck/boost (charge pumps) voltage regulation logic.
The regression and configuration scripts are updated with a generic
voltage domain for the system, and one for the CPUs.
This patch moves the instantiation of the memory controller outside
FSConfig and instead relies on the mem_ranges to pass the information
to the caller (e.g. fs.py or one of the regression scripts). The main
motivation for this change is to expose the structural composition of
the memory system and allow more tuning and configuration without
adding a large number of options to the makeSystem functions.
The patch updates the relevant example scripts to maintain the current
functionality. As the order that ports are connected to the memory bus
changes (in certain regresisons), some bus stats are shuffled
around. For example, what used to be layer 0 is now layer 1.
Going forward, options will be added to support the addition of
multi-channel memory controllers.
This patch contains three fixes to max tick options handling in Options.py and
Simulation.py:
1) Since the global simulator frequency isn't bound until m5.instantiate()
is called, the maxtick resolution needs to happen after this call, since
changes to the global frequency will cause m5.simulate() to misinterpret the
maxtick value. Shuffling this also requires tweaking the checkpoint directory
handling to signal the checkpoint restore tick back to run(). Fixing this
completely and correctly will require storing the simulation frequency into
checkpoints, which is beyond the scope of this patch.
2) The maxtick option in Options.py was defaulted to MaxTicks, so the old code
would always skip over the maxtime part of the conditionals at the beginning
of run(). Change the maxtick default to None, and set the maxtick local
variable in run() appropriately.
3) To clarify whether max ticks settings are relative or absolute, split the
maxtick option into separate options, for relative and absolute. Ensure that
these two options and the maxtime option are handled appropriately to set the
maxtick variable in Simulation.py.
The configuration scripts provided for ruby assume that the available
physical memory is equally distributed amongst the directory controllers.
But there is no check to ensure this assumption has been adhered to. This
patch adds the required check.
This patch adds the notion of source- and derived-clock domains to the
ClockedObjects. As such, all clock information is moved to the clock
domain, and the ClockedObjects are grouped into domains.
The clock domains are either source domains, with a specific clock
period, or derived domains that have a parent domain and a divider
(potentially chained). For piece of logic that runs at a derived clock
(a ratio of the clock its parent is running at) the necessary derived
clock domain is created from its corresponding parent clock
domain. For now, the derived clock domain only supports a divider,
thus ensuring a lower speed compared to its parent. Multiplier
functionality implies a PLL logic that has not been modelled yet
(create a separate clock instead).
The clock domains should be used as a mechanism to provide a
controllable clock source that affects clock for every clocked object
lying beneath it. The clock of the domain can (in a future patch) be
controlled by a handler responsible for dynamic frequency scaling of
the respective clock domains.
All the config scripts have been retro-fitted with clock domains. For
the System a default SrcClockDomain is created. For CPUs that run at a
different speed than the system, there is a seperate clock domain
created. This domain incorporates the CPU and the associated
caches. As before, Ruby runs under its own clock domain.
The clock period of all domains are pre-computed, such that no virtual
functions or multiplications are needed when calling
clockPeriod. Instead, the clock period is pre-computed when any
changes occur. For this to be possible, each clock domain tracks its
children.
This patch adds a 'sys_clock' command-line option and use it to assign
clocks to the system during instantiation.
As part of this change, the default clock in the System class is
removed and whenever a system is instantiated a system clock value
must be set. A default value is provided for the command-line option.
The configs and tests are updated accordingly.
