Simulating a SMP or multicore requires devices to be shared between
multiple KVM vCPUs. This means that locking is required when accessing
devices. This changeset adds the necessary locking to allow devices to
execute correctly. It is implemented by temporarily migrating the KVM
CPU to the VM's (and devices) event queue when handling
MMIO. Similarly, the VM migrates to the interrupt controller's event
queue when delivering an interrupt.
The support for fast-forwarding of multicore simulations added by this
changeset assumes that all devices in a system are simulated in the
same thread and each vCPU has its own thread. Special care must be
taken to ensure that devices living under the CPU in the object
hierarchy (e.g., the interrupt controller) do not inherit the parent
CPUs thread and are assigned to device thread. The KvmVM object is
assumed to live in the same thread as the other devices in the system.
The calling thread is undefined when the PollQueue services events.
This implies that PollEvents need to handle the case where they are
processed from a different thread than the thread that created the
event. This changeset adds temporary event queue migrations to the VNC
server, the ethernet tap device, and the terminal to protect them from
inter-thread calls.
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.
We need the ability to lock event queues to enable device accesses
across threads. The serviceOne() method now takes a service lock prior
to handling a new event. By locking an event queue, a different
thread/eq can effectively execute in the context of the locked event
queue. To simplify temporary event queue migrations, this changeset
introduces the EventQueue::ScopedMigration class that unlocks the
current event queue, locks a new event queue, and updates the current
event queue variable.
In order to prevent deadlocks, event queues need to be released when
waiting on barriers. This is implemented using the
EventQueue::ScopedRelease class. An instance of this class is, for
example, used in the BaseGlobalEvent class to release the event queue
when waiting on the synchronization barrier.
The intended use for this functionality is when devices need to be
accessed across thread boundaries. For example, when fast-forwarding,
it might be useful to run devices and CPUs in separate threads. In
such a case, the CPU locks the device queue whenever it needs to
perform IO. This functionality is primarily intended for KVM.
Note: Migrating between event queues can lead to non-deterministic
timing. Use with extreme care!
--HG--
extra : rebase_source : 23e3a741a1fd73861d1339782dbbe1bc76285315
1) fixes a typo for clean target libgemOpJni.so -> libgem5OpJni.so
2) addes jni_gem5Op.h to clean since it is added during make
3) links the m5 utility statically since it won't work on some images otherwise
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 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 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 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.
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.
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'.
