This patch fixes violation of TSO in the O3CPU, as all loads must be
ordered with all other loads. In the LQ, if a snoop is observed, all
subsequent loads need to be squashed if the system is TSO.
Prior to this patch, the following case could be violated:
P0 | P1 ;
MOV [x],mail=/usr/spool/mail/nilay | MOV EAX,[y] ;
MOV [y],mail=/usr/spool/mail/nilay | MOV EBX,[x] ;
exists (1:EAX=1 /\ 1:EBX=0) [is a violation]
The problem was found using litmus [http://diy.inria.fr].
Committed by: Nilay Vaish <nilay@cs.wisc.edu
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.
This patch enables a new 'DRAM' mode to the existing traffic
generator, catered to generate specific requests to DRAM based on
required hit length (stride size) and bank utilization. It is an add on
to the Random mode.
The basic idea is to control how many successive packets target the
same page, and how many banks are being used in parallel. This gives a
two-dimensional space that stresses different aspects of the DRAM
timing.
The configuration file needed to use this patch has to be changed as
follow: (reference to Random Mode, LPDDR3 memory type)
'STATE 0 10000000000 RANDOM 50 0 134217728 64 3004 5002 0'
-> 'STATE 0 10000000000 DRAM 50 0 134217728 32 3004 5002 0 96 1024 8 6 1'
The last 4 parameters to be added are:
<stride size (bytes), page size(bytes), number of banks available in DRAM,
number of banks to be utilized, address mapping scheme>
The address mapping information is used to get the stride address
stream of the specified size and to know where to find the bank
bits. The configuration file has a parameter where '0'-> RoCoRaBaCh,
'1'-> RoRaBaCoCh/RoRaBaChCo address-mapping schemes. Note that the
generator currently assumes a single channel and a single rank. This
is to avoid overwhelming the traffic generator with information about
the memory organisation.
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 patch moves the Ruby-related debug flags to the ruby
sub-directory, and also removes the state SConsopts that add the
no-longer-used NO_VECTOR_BOUNDS_CHECK.
Prevent incomplete configuration of TrafficGen class from causing
segmentation faults. If an 'INIT' line is not present in the
configuration file then the currState variable will remain
uninitialized which may result in a crash.
There were several sections of the m5ops code which were
essentially copy/pasted versions of the 32-bit code. The
problem is that some of these didn't account fo4 64-bit
registers leading to arguments being in the wrong registers.
This patch addresses the args for readfile64, writefile64,
and addsymbol64 -- all of which seemed to suffer from a
similar set of problems when moving to 64-bit.
Each consumer object maintains a set of tick values when the object is supposed
to wakeup and do some processing. As of now, the object accesses this set both
when scheduling a wakeup event and when the object actually wakes up. The set
is accessed during wakeup to remove the current tick value from the set. This
functionality is now being moved to the scheduling function where ticks are
removed at a later time.
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.
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.
KVM used to use two signals, one for instruction count exits and one
for timer exits. There is really no need to distinguish between the
two since they only trigger exits from KVM. This changeset unifies and
renames the signals and adds a method, kick(), that can be used to
raise the control signal in the vCPU thread. It also removes the early
timer warning since we do not normally see if the signal was
delivered.
--HG--
extra : rebase_source : cd0e45ca90894c3d6f6aa115b9b06a1d8f0fda4d
gem5 seems to store the PC as RIP+CS_BASE. This is not what KVM
expects, so we need to subtract CS_BASE prior to transferring the PC
into KVM. This changeset adds the necessary PC manipulation and
refactors thread context updates slightly to avoid reading registers
multiple times from KVM.
--HG--
extra : rebase_source : 3f0569dca06a1fcd8694925f75c8918d954ada44
This changeset adds support for INIT and STARTUP IPI handling. We
currently handle both of these interrupts in gem5 and transfer the
state to KVM. Since we do not have a BIOS loaded, we pretend that the
INIT interrupt suspends the CPU after reset.
--HG--
extra : rebase_source : 7f3b25f3801d68f668b6cd91eaf50d6f48ee2a6a
The table walker code currently accounts for two types of walks,
Atomic and Timing, and treats them differently. Atomic walks keep a
single instance of WalkerState around for all walks to use in
currState. Timing mode keeps a queue of in-flight WalkerStates and
maintains currState as NULL between walks.
If a functional walk is done during Timing mode, it is treated as an
atomic walk and either creates a persistent WalkerState if in between
Timing walks, or stomps an existing currState for an in-progress
Timing walk.
This patch distinguishes functional walks as being able to exist at
any time and sets up a temporary WalkerState for its exclusive use and
then cleans up when finished, leaving any in progress Atomic or Timing
walks undisturbed.
This patch fixes an assert condition that is not true at all
times. There are valid situations that arise in dual-core
dual-workload runs where the assert condition is false. The function
call following the assert however needs to be called only when the
condition is true (a block cannot be invalidated in the tags structure
if has not been allocated in the structure, and the tempBlock is never
allocated). Hence the 'assert' has been replaced with an 'if'.
This patch changes the decode script to output the optional fields of
the proto message Packet, namely id and flags. The flags field is set
by the communication monitor.
The id field is useful for CPU trace experiments, e.g. linking the
fetch side to decode side. It had to be renamed because it clashes
with a built in python function id() for getting the "identity" of an
object.
This patch also takes a few common function definitions out from the
multiple scripts and adds them to a protolib python module.
This snippet can be used to replace if + {panics, fatals, asserts} constructs.
The idea is to have both the condition checking and a verbose printout in a single statement. The interface is as follows:
panic_if(foo != bar, "These should be equal: foo %i bar %i", foo, bar);
fatal_if(foo != bar, "These should be equal: foo %i bar %i", foo, bar);
chatty_assert(foo == bar, "These should be equal: foo %i bar %i", foo, bar);
Small fix for a warning that prevents compilation with gcc 4.8.1 due
to detecting that a variable might be uninitialised. The fix is to
assign a safe default.
The global synchronization event used to be scheduled at
simQuantum. This prevented repeated entries into gem5 from Python as
it can be scheduled in the past. This changeset ensures that the first
global synchronization happens at curTick() + simQuantum instead.
The TSL/LDT & TR/TSS segments didn't contain valid attributes. This
caused problems when transfering the state into KVM where invalid
state is a no-go. Fixup the attributes with values from AMD's
architecture programmer's manual.
When transferring segment registers into kvm, we need to find the
value of the unusable bit. We used to assume that this could be
inferred from the selector since segments are generally unusable if
their selector is 0. This assumption breaks in some weird corner
cases. Instead, we just assume that segments are always usable. This
is what qemu does so it should work.
Signal handlers in KVM are controlled per thread and should be
initialized from the thread that is going to execute the CPU. This
changeset moves the initialization call from startup() to
startupThread().
A copyRegs() function is added to MIPS utilities
to copy architectural state from the old CPU to
the new CPU during fast-forwarding. This
addition alone enables fast-forwarding for the
o3 cpu model running MIPS.
The patch also adds takeOverFrom() and
drainResume() functions to the InOrderCPU to
enable it to take over from another CPU. This
change enables fast-forwarding for the inorder
cpu model running MIPS, but not for Alpha.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
Couple of users observed segmentation fault when the simulator tries to
register the statistical variable m_IncompleteTimes. It seems that there
is some problem with the initialization of these variables when allocated
in the constructor.
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.
This patch simplfies the retry logic in the RubyPort, avoiding
redundant attributes, and enforcing more stringent checks on the
interactions with the normal ports. The patch also simplifies the
routing done by the RubyPort, using the port identifiers instead of a
heavy-weight sender state.
The patch also fixes a bug in the sending of responses from PIO
ports. Previously these responses bypassed the queue in the queued
port, and ignored the return value, potentially leading to response
packets being lost.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
Code in two of the functions was exactly the same. This patch moves
this code to a new function which is called from the two functions
mentioned initially.
