There are two changes this patch makes to the way configurable members of a
state machine are specified in SLICC. The first change is that the data
member declarations will need to be separated by a semi-colon instead of a
comma. Secondly, the default value to be assigned would now use SLICC's
assignment operator i.e. ':='.
This patch changes the grammar for SLICC so as to remove some of the
redundant / duplicate rules. In particular rules for object/variable
declaration and class member declaration have been unified. Similarly, the
rules for a general function and a class method have been unified.
One more change is in the priority of two rules. The first rule is on
declaring a function with all the params typed and named. The second rule is
on declaring a function with all the params only typed. Earlier the second
rule had a higher priority. Now the first rule has a higher priority.
This patch enables the use of page tables that are stored in system memory
and respect x86 specification, in SE mode. It defines an architectural
page table for x86 as a MultiLevelPageTable class and puts a placeholder
class for other ISAs page tables, giving the possibility for future
implementation.
This patch defines a multi-level page table class that stores the page table in
system memory, consistent with ISA specifications. In this way, cpu models that
use the actual hardware to execute (e.g. KvmCPU), are able to traverse the page
table.
This patch ensures the cycle check is still valid even restoring from
a checkpoint. In this case the DRAMSim2 cycle count is relative to the
startTick rather than 0.
This patch fixes a bug in the DRAM controller address decoding. In
cases where the DRAM burst size (e.g. 32 bytes in a rank with a single
LPDDR3 x32) was smaller than the channel interleaving size
(e.g. systems with a 64-byte cache line) one address bit effectively
got used as a channel bit when it should have been a low-order column
bit.
This patch adds a notion of "columns per stripe", and more clearly
deals with the low-order column bits and high-order column bits. The
patch also relaxes the granularity check such that it is possible to
use interleaving granularities other than the cache line size.
The patch also adds a missing M5_CLASS_VAR_USED to the tCK member as
it is only used in the debug build for now.
When a cacheline is written back to a lower-level cache,
tags->insertBlock() sets various status parameters. However these
status bits were cleared immediately after calling. This patch makes
it so that these status fields are not cleared by moving them outside
of the tags->insertBlock() call.
this patch implements a new tags class that uses a random replacement policy.
these tags prefer to evict invalid blocks first, if none are available a
replacement candidate is chosen at random.
this patch factors out the common code in the LRU class and creates a new
abstract class: the BaseSetAssoc class. any set associative tag class must
implement the functionality related to the actual replacement policy in the
following methods:
accessBlock()
findVictim()
insertBlock()
invalidate()
This patch adds a DRAMPower flag to enable off-line DRAM power
analysis using the DRAMPower tool. A new DRAMPower flag is added
and a follow-on patch adds a Python script to post-process the output
and order it based on time stamps.
The long-term goal is to link DRAMPower as a library and provide the
commands through function calls to the model rather than first
printing and then parsing the commands. At the moment it is also up to
the user to ensure that the same DRAM configuration is used by the
gem5 controller model and DRAMPower.
This patch adds the index of the bank and rank as a field so that we can
determine the identity of a given bank (reference or pointer) for the
power tracing. We also grab the opportunity of cleaning up the
arguments used for identifying the bank when activating.
Using '== true' in a boolean expression is totally redundant,
and using '== false' is pretty verbose (and arguably less
readable in most cases) compared to '!'.
It's somewhat of a pet peeve, perhaps, but I had some time
waiting for some tests to run and decided to clean these up.
Unfortunately, SLICC appears not to have the '!' operator,
so I had to leave the '== false' tests in the SLICC code.
This patch makes a more firm connection between the DDR3-1600
configuration and the corresponding datasheet, and also adds a
DDR3-2133 and a DDR4-2400 configuration. At the moment there is also
an ongoing effort to align the choice of datasheets to what is
available in DRAMPower.
This patch extends the current timing parameters with the DRAM cycle
time. This is needed as the DRAMPower tool expects timestamps in DRAM
cycles. At the moment we could get away with doing this in a
post-processing step as the DRAMPower execution is separate from the
simulation run. However, in the long run we want the tool to be called
during the simulation, and then the cycle time is needed.
This patch adds the basic ingredients for a precharge all operation,
to be used in conjunction with DRAM power modelling.
Currently we do not try and apply any cleverness when precharging all
banks, thus even if only a single bank is open we use PREA as opposed
to PRE. At the moment we only have a single tRP (tRPpb), and do not
model the slightly longer all-bank precharge constraint (tRPab).
This patch adds the tRTP timing constraint, governing the minimum time
between a read command and a precharge. Default values are provided
for the existing DRAM types.
This patch merges the two control paths used to estimate the latency
and update the bank state. As a result of this merging the computation
is now in one place only, and should be easier to follow as it is all
done in absolute (rather than relative) time.
As part of this change, the scheduling is also refined to ensure that
we look at a sensible estimate of the bank ready time in choosing the
next request. The bank latency stat is removed as it ends up being
misleading when the DRAM access code gets evaluated ahead of time (due
to the eagerness of waking the model up for scheduling the next
request).
This patch adds the write recovery time to the DRAM timing
constraints, and changes the current tRASDoneAt to a more generic
preAllowedAt, capturing when a precharge is allowed to take place.
The part of the DRAM access code that accounts for the precharge and
activate constraints is updated accordingly.
This patch adds power states to the controller. These states and the
transitions can be used together with the Micron power model. As a
more elaborate use-case, the transitions can be used to drive the
DRAMPower tool.
At the moment, the power-down modes are not used, and this patch
simply serves to capture the idle, auto refresh and active modes. The
patch adds a third state machine that interacts with the refresh state
machine.
This patch adds a state machine for the refresh scheduling to
ensure that no accesses are allowed while the refresh is in progress,
and that all banks are propely precharged.
As part of this change, the precharging of banks of broken out into a
method of its own, making is similar to how activations are dealt
with. The idle accounting is also updated to ensure that the refresh
duration is not added to the time that the DRAM is in the idle state
with all banks precharged.
This patch changes the read/write event loop to use a single event
(nextReqEvent), along with a state variable, thus joining the two
control flows. This change makes it easier to follow the state
transitions, and control what happens when.
With the new loop we modify the overly conservative switching times
such that the write-to-read switch allows bank preparation to happen
in parallel with the bus turn around. Similarly, the read-to-write
switch uses the introduced tRTW constraint.
This patch squashes prefetch requests from downstream caches,
so that they do not steal cachelines away from caches closer
to the cpu. It was originally coded by Mitch Hayenga and
modified by Aasheesh Kolli.
Splits the CommMonitor trace_file parameter into three parameters. Previously,
the trace was only enabled if the trace_file parameter was set, and would be
written to this file. This patch adds in a trace_enable and trace_compress
parameter to the CommMonitor.
No trace is generated if trace_enable is set to False. If it is set to True, the
trace is written to a file based on the name of the SimObject in the simulation
hierarchy. For example, system.cluster.il1_commmonitor.trc. This filename can be
overridden by additionally specifying a file name to the trace_file parameter
(more on this later).
The trace_compress parameter will append .gz to any filename if set to True.
This enables compression of the generated traces. If the file name already ends
in .gz, then no changes are made.
The trace_file parameter will override the name set by the trace_enable
parameter. In the case that the specified name does not end in .gz but
trace_compress is set to true, .gz is appended to the supplied file name.
This never actually worked since it was printing out only a word
of the cache block and not the entire thing and doubly didn't work
csprintf overrides the %#x specifier and assumes a char* array is
actually a string.
Upon aggregating records, serialize system's cache-block size, as the
cache-block size can be different when restoring from a checkpoint. This way,
we can correctly read all records when restoring from a checkpoints, even if
the cache-block size is different.
Note, that it is only possible to restore from a checkpoint if the
desired cache-block size is smaller or equal to the cache-block size
when the checkpoint was taken; we can split one larger request into
multiple small ones, but it is not reliable to do the opposite.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
As of now, the enqueue statement can take in any number of 'pairs' as
argument. But we only use the pair in which latency is the key. This
latency is allowed to be either a fixed integer or a member variable of
controller in which the expression appears. This patch drops the use of pairs
in an enqueue statement. Instead, an expression is allowed which will be
interpreted to be the latency of the enqueue. This expression can anything
allowed by slicc including a constant integer or a member variable.
This patch adds stats for tracking the number of reads/writes per bus
turn around, and also adds hysteresis to the write-to-read switching
to ensure that the queue does not oscilate around the low threshold.
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 basic starvation-prevention mechanism where a DRAM
page is forced to close after a certain number of accesses. The limit
is combined with the open and open-adaptive page policy and if reached
causes an auto-precharge.
This patch changes the triggering condition for the write draining
such that we grab the opportunity to issue writes if there are no
reads waiting (as opposed to waiting for the writes to reach the high
threshold). As a result, we potentially drain some of the writes in read
idle periods (if any).
A low threshold is added to be able to control how many write bursts
are kept in the memory controller queue (acting as on-chip storage).
The high and low thresholds are updated to sensible values for a 32/64
size write buffer. Note that the thresholds should be adjusted along
with the queue sizes.
This patch also adds some basic initialisation sanity checks and moves
part of the initialisation to the constructor.
