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2017-11-20pwr: Adds logic to enter power gating for the cpu modelAnouk Van Laer
If the CPU has been clock gated for a sufficient amount of time (configurable via pwrGatingLatency), the CPU will go into the OFF power state. This does not model hardware, just behaviour. Change-Id: Ib3681d1ffa6ad25eba60f47b4020325f63472d43 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/3969 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-11-14cpu, probe: Fix elastic trace register dependencyRadhika Jagtap
Change-Id: I017852eac183fac3f914fdb96d7e72a56ea9d682 Reviewed-by: Nathanael Premillieu <nathanael.premillieu@arm.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/5121 Reviewed-by: Matthias Jung <jungma@eit.uni-kl.de> Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-10-19cpu-o3: Add M5_VAR_USED to variableJason Lowe-Power
Fixes compile error for gem5.fast on CLANG due to unused variable. Change-Id: Iabe777a27d75ee8bfa7b214fff577aed3c7582c7 Signed-off-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-on: https://gem5-review.googlesource.com/4980 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
2017-10-13cpu-o3: Check predication before the SQ size for a debug printNikos Nikoleris
The size of the store entry in the LSQ is used to indicate a fault in the execution of the store. At the same time, a store that is predicated false will also have 0 size in the corresponding store queue entry. This changeset ensures that we check if the store was predicated false before checking the size field. This way we avoid printing stores as faulting when they are only predicated false. Change-Id: Ie07982197bd73d7b44d26a3257d54ecb103a952a Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/4821 Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-10-13cpu-o3: Avoid early checker verification for store conditionalsNikos Nikoleris
The O3CPU allows stores to commit before they are completed and as soon as they enter the store queue. This is the reason why stores are verified by the the checker CPU, separately, once they complete and after they are sent to the memory. Store conditionals, on the other hand, have an additional writeback stage in the pipeline as they return their result to a register, similarly to loads. This is the reason why they do not commit before they receive a response from the memory. This allows store conditionals to be verified by the checker CPU as soon as they commit in the same way as all other non-store insturctions. At the same time, the presense of a checker CPU should not require changes to way we handle instructions. This change removes explicit calls to: * incorrectly set the extra data of the request to 0 (a subsequent call to completeAcc already does this without making any ISA assumptions about the return value of the failed store conditional) * complete failing store conditionals Change-Id: If21d70b21caa55b35e9fdcc50f254c590465d3c3 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/4820 Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-09-11stats: Get rid of some kernel stats related cruft.Gabe Black
The kernel stat mechanism should really be refactored and moved somewhere else, but in the mean time there's some old cruft that can be cleared away. Change-Id: I21e725de590dda0d20bf3bc675bbe976c7b1bd86 Reviewed-on: https://gem5-review.googlesource.com/4600 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-09-06cpu: Fix bi-mode branch predictor thresholdsRico Amslinger
When different sizes were set for the choice and global saturation counter (e.g. ex5_big), the threshold calculation used the wrong size. Thus the branch predictor always predicted "not taken" for choice > global. Change-Id: I076549ff1482e2280cef24a0d16b7bb2122d4110 Reviewed-on: https://gem5-review.googlesource.com/4560 Reviewed-by: Curtis Dunham <curtis.dunham@arm.com> Maintainer: Jason Lowe-Power <jason@lowepower.com>
2017-09-01cpu-minor: Fix for addr range coverage calculationPau Cabre
Coverage was wrongly set to PartialAddrRangeCoverage in the case of disjoint adjacent ranges Change-Id: I29aaf5145e6cdcf5f0b8f4e009d57ee57bd4c944 Signed-off-by: Pau Cabre <pau.cabre@metempsy.com> Reviewed-on: https://gem5-review.googlesource.com/4640 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-08-30cpu-o3: fix data pkt initialization for split loadMatthias Hille
When a split load hits a memory region where IPRs are mapped, the Writebackevent which is scheduled for that was carrying a data packet that was not correctly initialized which caused an assertion to fire when the Writeback event is processed. Change-Id: I71a4e291f0086f7468d7e8124a0a8f098088972f Signed-off-by: Matthias Hille <matthiashille8@gmail.com> Reported-by: Matthias Hille <matthiashille8@gmail.com> Reviewed-on: https://gem5-review.googlesource.com/4620 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Gabe Black <gabeblack@google.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-08-01kvm: Add a helper method to access device event queuesAndreas Sandberg
The VM's event queue is normally used for devices in multi-core KVM mode. Add a helper method, BaseKvmCPU::deviceEventQueue(), to access this queue. This makes the intention of code migrating to device event queues clearer. Change-Id: Ifb10f553a6d7445c8d562f658cf9d0b1f4c577ff Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-on: https://gem5-review.googlesource.com/4287 Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
2017-08-01cpu, kvm: Fix deadlock issue when resuming a drained systemAndreas Sandberg
The KVM CPU sometimes needs to access devices when drain() is called. This typically happens on ARM when synchronizing devices that use the system register interface. When called from drain(), the event queue isn't locked since drain is called from the outside when the simulator isn't servicing any events. In such cases, performing a migration to the device's queue will unlock a mutex that isn't locked. This typically results in a deadlock when resuming the system since the lock will be in an undefined state. Change-Id: Ibdcc2e034e916a929124f297e72aae306cf66728 Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Curtis Dunham <curtis.dunham@arm.com> Reviewed-on: https://gem5-review.googlesource.com/4286 Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
2017-07-19cpu: Add missing rename of vector registers in the O3 CPURekai Gonzalez-Alberquilla
The introduction of a new vector register class broke rename in the O3 CPU due to an unhandled register class in DefaultRename<Impl>::renameSrcRegs(). This patch fixes adds the necessary handling to avoid a panic when the vector register file is used. Change-Id: Ie380ab35ec4a151db15402f25b25b58931ee0581 Reviewed-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/4140 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-07-17cpu,o3: Fixed checkpointing bug occuring in the o3 CPUAnouk Van Laer
Checkpointing a system with out-of-order CPUs might get stuck if one of the CPUs has been put to sleep. The quiesce instruction cannot get drained hence checkpointing never finishes. This commit resolves that by activating all suspended thread contexts when draining the system. Change-Id: I817ab1672b4ead777bd8e12a0445829481c46fdc Reviewed-by: Sascha Bischoff <sascha.bischoff@arm.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/3970 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Jason Lowe-Power <jason@lowepower.com>
2017-07-12testers: Refactor some Event subclasses to lambdasSean Wilson
Change-Id: I897b6162a827216b7bad74d955c0e50e06a5a3ec Signed-off-by: Sean Wilson <spwilson2@wisc.edu> Reviewed-on: https://gem5-review.googlesource.com/3926 Maintainer: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
2017-07-12kvm, mem: Refactor some Event subclasses into lambdasSean Wilson
Change-Id: Ifafdcf4692d58a17f90e66ff8de8fa3e146c34bb Signed-off-by: Sean Wilson <spwilson2@wisc.edu> Reviewed-on: https://gem5-review.googlesource.com/3924 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-07-12cpu: Refactor some Event subclasses to lambdasSean Wilson
Change-Id: If765c6100d67556f157e4e61aa33c2b7eeb8d2f0 Signed-off-by: Sean Wilson <spwilson2@wisc.edu> Reviewed-on: https://gem5-review.googlesource.com/3923 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Jason Lowe-Power <jason@lowepower.com>
2017-07-12cpu, sim: Add param to force CPUs to wait for GDBJose Marinho
By setting the BaseCPU parameter wait_for_dbg_connection, the GDB server blocks during initialisation waiting for the remote debugger to connect before starting the simulated CPU. Change-Id: I4d62c68ce9adf69344bccbb44f66e30b33715a1c [ Update info message to include remote GDB port, rename param. ] Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/3963 Reviewed-by: Gabe Black <gabeblack@google.com> Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
2017-07-07kvm, arm: Don't forward IRQ/FIQ when using the kernel's GICAndreas Sandberg
The BaseArmKvmCPU is responsible for forwarding the IRQ and FIQ signals from gem5's simulated GIC to KVM. However, these signals shouldn't be used when the in-kernel GIC emulator is used. Instead of delivering the interrupts to the guest, we should just ignore them since any such pending interrupts are likely to be an artifact of CPU switching or incorrect draining. Change-Id: I083b72639384272157f92f44a6606bdf0be7413c Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Sudhanshu Jha <sudhanshu.jha@arm.com> Reviewed-by: Curtis Dunham <curtis.dunham@arm.com> Reviewed-on: https://gem5-review.googlesource.com/3660
2017-07-05arch: ISA parser additions of vector registersRekai Gonzalez-Alberquilla
Reiley's update :) of the isa parser definitions. My addition of the vector element operand concept for the ISA parser. Nathanael's modification creating a hierarchy between vector registers and its constituencies to the isa parser. Some fixes/updates on top to consider instructions as vectors instead of floating when they use the VectorRF. Some counters added to all the models to keep faithful counts. Change-Id: Id8f162a525240dfd7ba884c5a4d9fa69f4050101 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2706 Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-07-05cpu: Added interface for vector reg fileRekai Gonzalez-Alberquilla
This patch adds some more functionality to the cpu model and the arch to interface with the vector register file. This change consists mainly of augmenting ThreadContexts and ExecContexts with calls to get/set full vectors, underlying microarchitectural elements or lanes. Those are meant to interface with the vector register file. All classes that implement this interface also get an appropriate implementation. This requires implementing the vector register file for the different models using the VecRegContainer class. This change set also updates the Result abstraction to contemplate the possibility of having a vector as result. The changes also affect how the remote_gdb connection works. There are some (nasty) side effects, such as the need to define dummy numPhysVecRegs parameter values for architectures that do not implement vector extensions. Nathanael Premillieu's work with an increasing number of fixes and improvements of mine. Change-Id: Iee65f4e8b03abfe1e94e6940a51b68d0977fd5bb Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> [ Fix RISCV build issues and CC reg free list initialisation ] Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2705
2017-07-05cpu: Result refactoringRekai Gonzalez-Alberquilla
The Result union used to collect the result of an instruction is now a class of its own, with its constructor, and explicit casting methods for cleanliness. This is also a stepping stone to have vector registers, and instructions that produce a vector register as output. Change-Id: I6f40c11cb5e835d8b11f7804a4e967aff18025b9 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2703 Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-07-05cpu: Simplify the rename interface and use RegIdRekai Gonzalez-Alberquilla
With the hierarchical RegId there are a lot of functions that are redundant now. The idea behind the simplification is that instead of having the regId, telling which kind of register read/write/rename/lookup/etc. and then the function panic_if'ing if the regId is not of the appropriate type, we provide an interface that decides what kind of register to read depending on the register type of the given regId. Change-Id: I7d52e9e21fc01205ae365d86921a4ceb67a57178 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> [ Fix RISCV build issues ] Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2702
2017-07-05cpu: Physical register structural + flat indexingNathanael Premillieu
Mimic the changes done on the architectural register indexes on the physical register indexes. This is specific to the O3 model. The structure, called PhysRegId, contains a register class, a register index and a flat register index. The flat register index is kept because it is useful in some cases where the type of register is not important (dependency graph and scoreboard for example). Instead of directly using the structure, most of the code is working with a const PhysRegId* (typedef to PhysRegIdPtr). The actual PhysRegId objects are stored in the regFile. Change-Id: Ic879a3cc608aa2f34e2168280faac1846de77667 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2701 Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-07-05arch, cpu: Architectural Register structural indexingNathanael Premillieu
Replace the unified register mapping with a structure associating a class and an index. It is now much easier to know which class of register the index is referring to. Also, when adding a new class there is no need to modify existing ones. Change-Id: I55b3ac80763702aa2cd3ed2cbff0a75ef7620373 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> [ Fix RISCV build issues ] Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2700
2017-06-20cpu, gpu-compute: Replace EventWrapper use with EventFunctionWrapperSean Wilson
Change-Id: Idd5992463bcf9154f823b82461070d1f1842cea3 Signed-off-by: Sean Wilson <spwilson2@wisc.edu> Reviewed-on: https://gem5-review.googlesource.com/3746 Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Jason Lowe-Power <jason@lowepower.com>
2017-05-15cpu: fix problem with forwarding and locked loadAlec Roelke
If a (regular) store is followed closely enough by a locked load that overlaps, the LSQ will forward the store's data to the locked load and never tell the cache about the locked load. As a result, the cache will not lock the address and all future store-conditional requests on that address will fail. This patch fixes that by preventing forwarding if the memory request is a locked load and adding another case to the LSQ forwarding logic that delays the locked load request if a store in the LSQ contains all or part of the data that is requested. [Merge second and last if blocks because their bodies are the same.] Change-Id: I895cc2b9570035267bdf6ae3fdc8a09049969841 Reviewed-on: https://gem5-review.googlesource.com/2400 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Tony Gutierrez <anthony.gutierrez@amd.com> Maintainer: Jason Lowe-Power <jason@lowepower.com>
2017-05-02python: Use PyBind11 instead of SWIG for Python wrappersAndreas Sandberg
Use the PyBind11 wrapping infrastructure instead of SWIG to generate wrappers for functionality that needs to be exported to Python. This has several benefits: * PyBind11 can be redistributed with gem5, which means that we have full control of the version used. This avoid a large number of hard-to-debug SWIG issues we have seen in the past. * PyBind11 doesn't rely on a custom C++ parser, instead it relies on wrappers being explicitly declared in C++. The leads to slightly more boiler-plate code in manually created wrappers, but doesn't doesn't increase the overall code size. A big benefit is that this avoids strange compilation errors when SWIG doesn't understand modern language features. * Unlike SWIG, there is no risk that the wrapper code incorporates incorrect type casts (this has happened on numerous occasions in the past) since these will result in compile-time errors. As a part of this change, the mechanism to define exported methods has been redesigned slightly. New methods can be exported either by declaring them in the SimObject declaration and decorating them with the cxxMethod decorator or by adding an instance of PyBindMethod/PyBindProperty to the cxx_exports class variable. The decorator has the added benefit of making it possible to add a docstring and naming the method's parameters. The new wrappers have the following known issues: * Global events can't be memory managed correctly. This was the case in SWIG as well. Change-Id: I88c5a95b6cf6c32fa9e1ad31dfc08b2e8199a763 Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Andreas Hansson <andreas.hansson@arm.com> Reviewed-by: Andrew Bardsley <andrew.bardsley@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2231 Reviewed-by: Tony Gutierrez <anthony.gutierrez@amd.com> Reviewed-by: Pierre-Yves Péneau <pierre-yves.peneau@lirmm.fr> Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
2017-04-03arm, kvm: implement GIC state transferCurtis Dunham
This also allows checkpointing of a Kvm GIC via the Pl390 model. Change-Id: Ic85d81cfefad630617491b732398f5e6a5f34c0b Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2444 Maintainer: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Weiping Liao <weipingliao@google.com>
2017-03-16cpu: Print progress messages in Trace CPURadhika Jagtap
This change adds the ability to print a message at intervals of committed instruction count to indicate progress in the trace replay. Change-Id: I8363502354c42bfc52936d2627986598b63a5797 Reviewed-by: Rekai Gonzalez Alberquilla <rekai.gonzalezalberquilla@arm.com> Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/2321 Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
2017-02-27syscall_emul: [PATCH 15/22] add clone/execve for threading and multiprocess ↵Brandon Potter
simulations Modifies the clone system call and adds execve system call. Requires allowing processes to steal thread contexts from other processes in the same system object and the ability to detach pieces of process state (such as MemState) to allow dynamic sharing.
2015-07-20syscall_emul: [patch 13/22] add system call retry capabilityBrandon Potter
This changeset adds functionality that allows system calls to retry without affecting thread context state such as the program counter or register values for the associated thread context (when system calls return with a retry fault). This functionality is needed to solve problems with blocking system calls in multi-process or multi-threaded simulations where information is passed between processes/threads. Blocking system calls can cause deadlock because the simulator itself is single threaded. There is only a single thread servicing the event queue which can cause deadlock if the thread hits a blocking system call instruction. To illustrate the problem, consider two processes using the producer/consumer sharing model. The processes can use file descriptors and the read and write calls to pass information to one another. If the consumer calls the blocking read system call before the producer has produced anything, the call will block the event queue (while executing the system call instruction) and deadlock the simulation. The solution implemented in this changeset is to recognize that the system calls will block and then generate a special retry fault. The fault will be sent back up through the function call chain until it is exposed to the cpu model's pipeline where the fault becomes visible. The fault will trigger the cpu model to replay the instruction at a future tick where the call has a chance to succeed without actually going into a blocking state. In subsequent patches, we recognize that a syscall will block by calling a non-blocking poll (from inside the system call implementation) and checking for events. When events show up during the poll, it signifies that the call would not have blocked and the syscall is allowed to proceed (calling an underlying host system call if necessary). If no events are returned from the poll, we generate the fault and try the instruction for the thread context at a distant tick. Note that retrying every tick is not efficient. As an aside, the simulator has some multi-threading support for the event queue, but it is not used by default and needs work. Even if the event queue was completely multi-threaded, meaning that there is a hardware thread on the host servicing a single simulator thread contexts with a 1:1 mapping between them, it's still possible to run into deadlock due to the event queue barriers on quantum boundaries. The solution of replaying at a later tick is the simplest solution and solves the problem generally.
2017-02-14sim, kvm: make KvmVM a System parameterCurtis Dunham
A KVM VM is typically a child of the System object already, but for solving future issues with configuration graph resolution, the most logical way to keep track of this object is for it to be an actual parameter of the System object. Change-Id: I965ded22203ff8667db9ca02de0042ff1c772220 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
2016-11-09style: [patch 3/22] reduce include dependencies in some headersBrandon Potter
Used cppclean to help identify useless includes and removed them. This involved erroneously included headers, but also cases where forward declarations could have been used rather than a full include.
2016-11-09style: [patch 1/22] use /r/3648/ to reorganize includesBrandon Potter
2017-01-03sim: Remove redundant export_method_cxx_predeclsAndreas Sandberg
The headers declared in export_method_cxx_predecls are redundant since a SimObject's main header is automatically included. Change-Id: Ied9e84630b36960e54efe91d16f8c66fba7e0da0 Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Curtis Dunham <curtis.dunham@arm.com> Reviewed-by: Joe Gross <joseph.gross@amd.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
2016-12-21cpu: implement an L-TAGE branch predictorArthur Perais
This patch implements an L-TAGE predictor, based on André Seznec's code available from CBP-2 (http://hpca23.cse.tamu.edu/taco/camino/cbp2/cbp-src/realistic-seznec.h). Signed-off-by Jason Lowe-Power <jason@lowepower.com>
2016-12-21cpu: disallow speculative update of branch predictor tables (o3)Arthur Perais
The Minor and o3 cpu models share the branch prediction code. Minor relies on the BPredUnit::squash() function to update the branch predictor tables on a branch mispre- diction. This is fine because Minor executes in-order, so the update is on the correct path. However, this causes the branch predictor to be updated on out-of-order branch mispredictions when using the o3 model, which should not be the case. This patch guards against speculative update of the branch prediction tables. On a branch misprediction, BPredUnit::squash() calls BpredUnit::update(..., squashed = true). The underlying branch predictor tests against the value of squashed. If it is true, it restores any speculatively updated internal state it might have (e.g., global/local branch history), then returns. If false, it updates its prediction tables. Previously, exist- ing predictors did not test against the "squashed" parameter. To accomodate for this change, the Minor model must now call BPredUnit::squash() then BPredUnit::update(..., squashed = false) on branch mispredictions. Before, calling BpredUnit::squash() performed the prediction tables update. The effect is a slight MPKI improvement when using the o3 model. A further patch should perform the same modifications for the indirect target predictor and BTB (less critical). Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
2016-12-21cpu: correct comments in tournament branch predictorArthur Perais
The tournament predictor is presented as doing speculative update of the global history and non-speculative update of the local history used to generate the branch prediction. However, the code does speculative update of both histories. Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
2016-12-21cpu: Resolve targets of predicted 'taken' decode for O3Arthur Perais
The target of taken conditional direct branches does not need to be resolved in IEW: the target can be computed at decode, usually using the decoded instruction word and the PC. The higher-than-necessary penalty is taken only on conditional branches that are predicted taken but miss in the BTB. Thus, this is mostly inconsequential on IPC if the BTB is big/associative enough (fewer capacity/conflict misses). Nonetheless, what gem5 simulates is not representative of how conditional branch targets can be handled. Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
2016-12-21cpu: Clarify meaning of cachePorts variable in lsq_unit.hh of O3Arthur Perais
cachePorts currently constrains the number of store packets written to the D-Cache each cycle), but loads currently affect this variable. This leads to unexpected congestion (e.g., setting cachePorts to a realistic 1 will in fact allow a store to WB only if no loads have accessed the D-Cache this cycle). In the absence of arbitration, this patch decouples how many loads can be done per cycle from how many stores can be done per cycle. Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
2016-12-05cpu: Change traffic generators to use different values for writesNikos Nikoleris
Previously all traffic generators would use the same value for write requests. With this change traffic generators use their master id as the payload of write requests making them more useful for the memchecker. Change-Id: Id1a6b8f02853789b108ef6003f4c32ab929bb123 Reviewed-by: Andreas Hansson <andreas.hansson@arm.com> Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
2016-11-30arch: [Patch 1/5] Added RISC-V base instruction set RV64IAlec Roelke
First of five patches adding RISC-V to GEM5. This patch introduces the base 64-bit ISA (RV64I) in src/arch/riscv for use with syscall emulation. The multiply, floating point, and atomic memory instructions will be added in additional patches, as well as support for more detailed CPU models. The loader is also modified to be able to parse RISC-V ELF files, and a "Hello world\!" example for RISC-V is added to test-progs. Patch 2 will implement the multiply extension, RV64M; patch 3 will implement the floating point (single- and double-precision) extensions, RV64FD; patch 4 will implement the atomic memory instructions, RV64A, and patch 5 will add support for timing, minor, and detailed CPU models that is missing from the first four patches (such as handling locked memory). [Removed several unused parameters and imports from RiscvInterrupts.py, RiscvISA.py, and RiscvSystem.py.] [Fixed copyright information in RISC-V files copied from elsewhere that had ARM licenses attached.] [Reorganized instruction definitions in decoder.isa so that they are sorted by opcode in preparation for the addition of ISA extensions M, A, F, D.] [Fixed formatting of several files, removed some variables and instructions that were missed when moving them to other patches, fixed RISC-V Foundation copyright attribution, and fixed history of files copied from other architectures using hg copy.] [Fixed indentation of switch cases in isa.cc.] [Reorganized syscall descriptions in linux/process.cc to remove large number of repeated unimplemented system calls and added implmementations to functions that have received them since it process.cc was first created.] [Fixed spacing for some copyright attributions.] [Replaced the rest of the file copies using hg copy.] [Fixed style check errors and corrected unaligned memory accesses.] [Fix some minor formatting mistakes.] Signed-off by: Alec Roelke Signed-off by: Jason Lowe-Power <jason@lowepower.com>
2016-11-30cpu: Remove branch predictor function predictInOrderJason Lowe-Power
This function was used by the now-defunct InOrderCPU model. Since this model is no longer in gem5, this function was not called from anywhere in the code.
2016-10-15cpu, arm: Distinguish Float* and SimdFloat*, create FloatMem* opClassFernando Endo
Modify the opClass assigned to AArch64 FP instructions from SimdFloat* to Float*. Also create the FloatMemRead and FloatMemWrite opClasses, which distinguishes writes to the INT and FP register banks. Change the latency of (Simd)FloatMultAcc to 5, based on the Cortex-A72, where the "latency" of FMADD is 3 if the next instruction is a FMADD and has only the augend to destination dependency, otherwise it's 7 cycles. Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
2016-10-06ruby: rename networktest to garnet_synthetic_traffic.Tushar Krishna
networktest is essentially a collection of synthetic traffic patterns for the network. The protocol name and the tester having the same name led to multiple python configuration files with the same name, adding confusion. This patch renames networktest to garnet_synthetic_traffic, and also adds more synthetic traffic patterns.
2016-09-22cpu: Fix the O3 CPU DrainRekai Gonzalez-Alberquilla
The drain did not wait until stages were ready again. Therefore, as a result of messages in the TimeBuffer being drain, the state after the drain was not consistent and asserts fired in some places when the draining happened after a stage got blocked, but before the notification arrived to the previous stages. Change-Id: Ib50b3b40b7f745b62c1eba2931dec76860824c71 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
2016-09-15cpu: Support exit when any one Trace CPU completes replayRadhika Jagtap
This change adds a Trace CPU param to exit simulation early, i.e. when the first (any one) trace execution is complete. With this change the user gets a choice to configure exit as either when the last CPU finishes (default) or first CPU finishes replay. Configuring an early exit enables simulating and measuring stats strictly when memory-system resources are being stressed by all Trace CPUs. Change-Id: I3998045fdcc5cd343e1ca92d18dd7f7ecdba8f1d Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
2016-09-15cpu: Adjust for trace offset and fix statsRadhika Jagtap
This change subtracts the time offset present in the trace from all the event times when nodes and request are sent so that the replay starts immediately when the simulation starts. This makes the stats accurate when the time offset in traces is large, for example when traces are generated in the middle of a workload execution. It also solves the problem of unnecessary DRAM refresh events that would keep occuring during the large time offset before even a single request is replayed into the system. Change-Id: Ie0898842615def867ffd5c219948386d952af7f7 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
2016-09-15cpu: Add frequency scaling to the Trace CPURadhika Jagtap
This change adds a simple feature to scale the frequency of the Trace CPU. The compute delays in the input traces provide timing. This change adds a freqency multiplier parameter to the Trace CPU set to 1.0 by default. The compute delay is manipulated to effectively achieve the frequency at which the nodes become ready and thus scale the frequency of the Trace CPU. Change-Id: Iaabbd57806941ad56094fcddbeb38fcee1172431 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
2016-09-13kvm: Support timing accesses for KVM cpuMichael LeBeane
This patch enables timing accesses for KVM cpu. A new state, RunningMMIOPending, is added to indicate that there are outstanding timing requests generated by KVM in the system. KVM's tick() is disabled and the simulation does not enter into KVM until all outstanding timing requests have completed. The main motivation for this is to allow KVM CPU to perform MMIO in Ruby, since Ruby does not support atomic accesses.