Commit graph

6665 commits

Author SHA1 Message Date
Steve Reinhardt
ee0b52404c mem: restructure Packet cmd initialization a bit more
Refactor the way that specific MemCmd values are generated for packets.
The new approach is a little more elegant in that we assign the right
value up front, and it's also more amenable to non-heap-allocated
Packet objects.

Also replaced the code in the Minor model that was still doing it the
ad-hoc way.

This is basically a refinement of http://repo.gem5.org/gem5/rev/711eb0e64249.
2015-02-11 10:48:50 -08:00
Steve Reinhardt
ccef61d1cc mem: clean up write buffer check in Cache::handleSnoop()
The 'if (writebacks.size)' check was redundant, because
writeBuffer.findMatches() would return false if the
writebacks list was empty.

Also renamed 'mshr' to 'wb_entry' in this context since
we are pointing at a writebuffer entry and not an MSHR
(even though it's the same C++ class).
2015-03-14 06:51:07 -07:00
Nilay Vaish
e5fbc67e16 cpu: o3: another assert instead of check 2015-03-09 09:39:08 -05:00
Nilay Vaish
5003ed5f7a cpu: o3: Remove unused code in iew, add assert instead. 2015-03-09 09:39:08 -05:00
Nilay Vaish
4e1d10a3cf cpu: o3: commit: mark pipeline delay variable as consts 2015-03-09 09:39:08 -05:00
Nilay Vaish
53de2512b1 cpu: o3: remove unused stat variables. 2015-03-09 09:39:08 -05:00
Nilay Vaish
54bc67f619 cpu: o3: combine if with same condition 2015-03-09 09:39:07 -05:00
Nilay Vaish
61edd5ac97 cpu: o3: remove member variable squashCounter
The variable is used in only one place and a whole new function setNextStatus()
has been defined just to compute the value of the variable.  Instead of calling
the function, the value is now computed in the loop that preceded the function
call.
2015-03-09 09:39:07 -05:00
Nilay Vaish
f69a74fda6 cpu: o3: remove unused function annotateMemoryUnits() 2015-03-09 09:39:07 -05:00
Andreas Hansson
fc315901ff mem: Unify all cache DPRINTF address formatting
This patch changes all the DPRINTF messages in the cache to use
'%#llx' every time a packet address is printed. The inclusion of '#'
ensures '0x' is prepended, and since the address type is a uint64_t %x
really should be %llx.
2015-03-02 04:00:56 -05:00
Andreas Hansson
88e2963951 mem: Fix cache MSHR conflict determination
This patch fixes a rather subtle issue in the sending of MSHR requests
in the cache, where the logic previously did not check for conflicts
between the MSRH queue and the write queue when requests were not
ready. The correct thing to do is to always check, since not having a
ready MSHR does not guarantee that there is no conflict.

The underlying problem seems to have slipped past due to the symmetric
timings used for the write queue and MSHR queue. However, with the
recent timing changes the bug caused regressions to fail.
2015-03-02 04:00:54 -05:00
Andreas Hansson
407737614e mem: Add byte mask to Packet::checkFunctional
This patch changes the valid-bytes start/end to a proper byte
mask. With the changes in timing introduced in previous patches there
are more packets waiting in queues, and there are regressions using
the checker CPU failing due to non-contigous read data being found in
the various cache queues.

This patch also adds some more comments explaining what is going on,
and adds the fourth and missing case to Packet::checkFunctional.
2015-03-02 04:00:52 -05:00
Stephan Diestelhorst
ecef1612b8 mem: Add option to force in-order insertion in PacketQueue
By default, the packet queue is ordered by the ticks of the to-be-sent
packages. With the recent modifications of packages sinking their header time
when their resposne leaves the caches, there could be cases of MSHR targets
being allocated and ordered A, B, but their responses being sent out in the
order B,A. This led to inconsistencies in bus traffic, in particular the snoop
filter observing first a ReadExResp and later a ReadRespWithInv.  Logically,
these were ordered the other way around behind the MSHR, but due to the timing
adjustments when inserting into the PacketQueue, they were sent out in the
wrong order on the bus, confusing the snoop filter.

This patch adds a flag (off by default) such that these special cases can
request in-order insertion into the packet queue, which might offset timing
slighty. This is expected to occur rarely and not affect timing results.
2015-03-02 04:00:49 -05:00
Marco Balboni
d4ef8368aa mem: Downstream components consumes new crossbar delays
This patch makes the caches and memory controllers consume the delay
that is annotated to a packet by the crossbar. Previously many
components simply threw these delays away. Note that the devices still
do not pay for these delays.
2015-03-02 04:00:48 -05:00
Andreas Hansson
36dc93a5fa mem: Move crossbar default latencies to subclasses
This patch introduces a few subclasses to the CoherentXBar and
NoncoherentXBar to distinguish the different uses in the system. We
use the crossbar in a wide range of places: interfacing cores to the
L2, as a system interconnect, connecting I/O and peripherals,
etc. Needless to say, these crossbars have very different performance,
and the clock frequency alone is not enough to distinguish these
scenarios.

Instead of trying to capture every possible case, this patch
introduces dedicated subclasses for the three primary use-cases:
L2XBar, SystemXBar and IOXbar. More can be added if needed, and the
defaults can be overridden.
2015-03-02 04:00:47 -05:00
Marco Balboni
d35dd71ab4 mem: Add crossbar latencies
This patch introduces latencies in crossbar that were neglected
before. In particular, it adds three parameters in crossbar model:
front_end_latency, forward_latency, and response_latency. Along with
these parameters, three corresponding members are added:
frontEndLatency, forwardLatency, and responseLatency. The coherent
crossbar has an additional snoop_response_latency.

The latency of the request path through the xbar is set as
--> frontEndLatency + forwardLatency

In case the snoop filter is enabled, the request path latency is charged
also by look-up latency of the snoop filter.
--> frontEndLatency + SF(lookupLatency) + forwardLatency.

The latency of the response path through the xbar is set instead as
--> responseLatency.

In case of snoop response, if the response is treated as a normal response
the latency associated is again
--> responseLatency;

If instead it is forwarded as snoop response we add an additional variable
+ snoopResponseLatency
and the latency associated is
--> snoopResponseLatency;

Furthermore, this patch lets the crossbar progress on the next clock
edge after an unused retry, changing the time the crossbar considers
itself busy after sending a retry that was not acted upon.
2015-03-02 04:00:46 -05:00
Andreas Sandberg
7be9d4eb67 dev, arm: Clean up PL011 and rewrite interrupt handling
The ARM PL011 UART model didn't clear and raise interrupts
correctly. This changeset rewrites the whole interrupt handling and
makes it both simpler and fixes several cases where the correct
interrupts weren't raised or cleared. Additionally, it cleans up many
other aspects of the code.
2015-03-02 04:00:44 -05:00
Andreas Hansson
d64b34bef8 arm: Share a port for the two table walker objects
This patch changes how the MMU and table walkers are created such that
a single port is used to connect the MMU and the TLBs to the memory
system. Previously two ports were needed as there are two table walker
objects (stage one and stage two), and they both had a port. Now the
port itself is moved to the Stage2MMU, and each TableWalker is simply
using the port from the parent.

By using the same port we also remove the need for having an
additional crossbar joining the two ports before the walker cache or
the L2. This simplifies the creation of the CPU cache topology in
BaseCPU.py considerably. Moreover, for naming and symmetry reasons,
the TLB walker port is connected through the stage-one table walker
thus making the naming identical to x86. Along the same line, we use
the stage-one table walker to generate the master id that is used by
all TLB-related requests.
2015-03-02 04:00:42 -05:00
Giacomo Gabrielli
bd70db5521 arm: Remove unnecessary dependencies between AArch64 FP instructions 2015-03-02 04:00:41 -05:00
Rekai
3d5434022a cpu: o3 register renaming request handling improved
Now, prior to the renaming, the instruction requests the exact amount of
registers it will need, and the rename_map decides whether the instruction is
allowed to proceed or not.
2015-03-02 04:00:38 -05:00
Andreas Hansson
987de4f5cc mem: Tidy up the cache debug messages
Avoid redundant inclusion of the name in the DPRINTF string.
2015-03-02 04:00:37 -05:00
Andreas Hansson
f26a289295 mem: Split port retry for all different packet classes
This patch fixes a long-standing isue with the port flow
control. Before this patch the retry mechanism was shared between all
different packet classes. As a result, a snoop response could get
stuck behind a request waiting for a retry, even if the send/recv
functions were split. This caused message-dependent deadlocks in
stress-test scenarios.

The patch splits the retry into one per packet (message) class. Thus,
sendTimingReq has a corresponding recvReqRetry, sendTimingResp has
recvRespRetry etc. Most of the changes to the code involve simply
clarifying what type of request a specific object was accepting.

The biggest change in functionality is in the cache downstream packet
queue, facing the memory. This queue was shared by requests and snoop
responses, and it is now split into two queues, each with their own
flow control, but the same physical MasterPort. These changes fixes
the previously seen deadlocks.
2015-03-02 04:00:35 -05:00
Ali Jafri
6ebe8d863a mem: Fix prefetchSquash + memInhibitAsserted bug
This patch resolves a bug with hardware prefetches. Before a hardware prefetch
is sent towards the memory, the system generates a snoop request to check all
caches above the prefetch generating cache for the presence of the prefetth
target. If the prefetch target is found in the tags or the MSHRs of the upper
caches, the cache sets the prefetchSquashed flag in the snoop packet. When the
snoop packet returns with the prefetchSquashed flag set, the prefetch
generating cache deallocates the MSHR reserved for the prefetch. If the
prefetch target is found in the writeback buffer of the upper cache, the cache
sets the memInhibit flag, which signals the prefetch generating cache to
expect the data from the writeback. When the snoop packet returns with the
memInhibitAsserted flag set, it marks the allocated MSHR as inService and
waits for the data from the writeback.

If the prefetch target is found in multiple upper level caches, specifically
in the tags or MSHRs of one upper level cache and the writeback buffer of
another, the snoop packet will return with both prefetchSquashed and
memInhibitAsserted set, while the current code is not written to handle such
an outcome. Current code checks for the prefetchSquashed flag first, if it
finds the flag, it deallocates the reserved MSHR. This leads to assert failure
when the data from the writeback appears at cache. In this fix, we simply
switch the order of checks. We first check for memInhibitAsserted and then for
prefetch squashed.
2015-03-02 04:00:34 -05:00
Stephan Diestelhorst
de46eeade7 cpu: Add a PC-value to the traffic generator requests
Have the traffic generator add its masterID as the PC address to the
requests. That way, prefetchers (and other components) that use a PC
for request classification will see per-tester streams of requests.
This enables us to test strided prefetchers with the memchecker, too.
2015-03-02 04:00:31 -05:00
Andreas Sandberg
3b4ae7debb arm: Don't truncate 16-bit ASIDs to 8 bits
The ISA code sometimes stores 16-bit ASIDs as 8-bit unsigned integers
and has a couple of inverted checks that mask out the high 8 bits of
an ASID if 16-bit ASIDs have been /enabled/. This changeset fixes both
of those issues.
2015-03-02 04:00:28 -05:00
Andreas Sandberg
804b11a3ed arm: Correctly access the stack pointer in GDB
We curently use INTREG_X31 instead of INTREG_SPX when accessing the
stack pointer in GDB. gem5 normally uses INTREG_SPX to access the
stack pointer, which gets mapped to the stack pointer corresponding
(INTREG_SPn) to the current exception level. This changeset updates
the GDB interface to use SPX instead of X31 (which is always zero)
when transfering CPU state to gdb.
2015-03-02 04:00:27 -05:00
Andreas Sandberg
34dcd90b61 arm: Fix broken page table permissions checks in remote GDB
The remote GDB interface currently doesn't check if translations are
valid before reading memory. This causes a panic when GDB tries to
access unmapped memory (e.g., when getting a stack trace). There are
two reasons for this: 1) The function used to check for valid
translations (virtvalid()) doesn't work and panics on invalid
translations. 2) The method in the GDB interface used to test if a
translation is valid (RemoteGDB::acc) always returns true regardless
of the return from virtvalid().

This changeset fixes both of these issues.
2015-03-02 04:00:27 -05:00
Jason Power
670f44e05e Ruby: Update backing store option to propagate through to all RubyPorts
Previously, the user would have to manually set access_backing_store=True
on all RubyPorts (Sequencers) in the config files.
Now, instead there is one global option that each RubyPort checks on
initialization.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2015-02-26 09:58:26 -06:00
Andreas Hansson
8c78aa31ea cpu: TrafficGen sinks snoops without complaining
To be able to use the TrafficGen in a system with caches we need to
allow it to sink incoming snoop requests. By default the master port
panics, so silently ignore any snoops.
2015-02-16 03:34:55 -05:00
Stephan Diestelhorst
93fa8e3cd4 mem: Fix initial value problem with MemChecker
In highly loaded cases, reads might actually overlap with writes to the
initial memory state. The mem checker needs to detect such cases and
permit the read reading either from the writes (what it is doing now) or
read from the initial, unknown value.

This patch adds this logic.
2015-02-16 03:34:47 -05:00
Andreas Hansson
661dac1598 dev: Fix undefined behaviuor in i8254xGBe
This patch fixes a rather unfortunate oversight where the annotation
pointer was used even though it is null. Somehow the code still works,
but UBSan is rather unhappy. The use is now guarded, and the variable
is initialised in the constructor (as well as init()).
2015-02-16 03:34:35 -05:00
Andreas Sandberg
0a2ee77616 arm: Wire up the GIC with the platform in the base class
Move the (common) GIC initialization code that notifies the platform
code of the new GIC to the base class (BaseGic) instead of the Pl390
implementation.
2015-02-16 03:34:18 -05:00
Andreas Hansson
e17328a227 mem: mmap the backing store with MAP_NORESERVE
This patch ensures we can run simulations with very large simulated
memories (at least 64 TB based on some quick runs on a Linux
workstation). In essence this allows us to efficiently deal with
sparse address maps without having to implement a redirection layer in
the backing store.

This opens up for run-time errors if we eventually exhausts the hosts
memory and swap space, but this should hopefully never happen.
2015-02-16 03:33:47 -05:00
Andreas Hansson
57758ca685 mem: Use the range cache for lookup as well as access
This patch changes the range cache used in the global physical memory
to be an iterator so that we can use it not only as part of isMemAddr,
but also access and functionalAccess. This matches use-cases where a
core is using the atomic non-caching memory mode, and repeatedly calls
isMemAddr and access.

Linux boot on aarch32, with a single atomic CPU, is now more than 30%
faster when using "--fastmem" compared to not using the direct memory
access.
2015-02-16 03:33:37 -05:00
Andreas Hansson
d0e1b8a19c arch: Make readMiscRegNoEffect const throughout
Finally took the plunge and made this apply to all ISAs, not just ARM.
2015-02-16 03:33:28 -05:00
Andreas Sandberg
5bfa7e3d59 arm: Merge ISA files with pseudo instructions
This changeset moves the pseudo instructions used to signal unknown
instructions and unimplemented instructions to the same source files
as the decoder fault.
2015-02-16 03:32:58 -05:00
Ali Saidi
4eff4fa12e cpu: add support for outputing a protobuf formatted CPU trace
Doesn't support x86 due to static instruction representation.

--HG--
rename : src/cpu/CPUTracers.py => src/cpu/InstPBTrace.py
2015-02-16 03:32:38 -05:00
Marco Balboni
268d9e59c5 mem: Clarification of packet crossbar timings
This patch clarifies the packet timings annotated
when going through a crossbar.

The old 'firstWordDelay' is replaced by 'headerDelay' that represents
the delay associated to the delivery of the header of the packet.

The old 'lastWordDelay' is replaced by 'payloadDelay' that represents
the delay needed to processing the payload of the packet.

For now the uses and values remain identical. However, going forward
the payloadDelay will be additive, and not include the
headerDelay. Follow-on patches will make the headerDelay capture the
pipeline latency incurred in the crossbar, whereas the payloadDelay
will capture the additional serialisation delay.
2015-02-11 10:23:47 -05:00
Marco Balboni
e2828587b3 mem: Clarify usage of latency in the cache
This patch adds some much-needed clarity in the specification of the
cache timing. For now, hit_latency and response_latency are kept as
top-level parameters, but the cache itself has a number of local
variables to better map the individual timing variables to different
behaviours (and sub-components).

The introduced variables are:
- lookupLatency: latency of tag lookup, occuring on any access
- forwardLatency: latency that occurs in case of outbound miss
- fillLatency: latency to fill a cache block
We keep the existing responseLatency

The forwardLatency is used by allocateInternalBuffer() for:
- MSHR allocateWriteBuffer (unchached write forwarded to WriteBuffer);
- MSHR allocateMissBuffer (cacheable miss in MSHR queue);
- MSHR allocateUncachedReadBuffer (unchached read allocated in MSHR
  queue)
It is our assumption that the time for the above three buffers is the
same. Similarly, for snoop responses passing through the cache we use
forwardLatency.
2015-02-11 10:23:36 -05:00
Andreas Hansson
6563ec8634 cpu: Tidy up the MemTest and make false sharing more obvious
The MemTest class really only tests false sharing, and as such there
was a lot of old cruft that could be removed. This patch cleans up the
tester, and also makes it more clear what the assumptions are. As part
of this simplification the reference functional memory is also
removed.

The regression configs using MemTest are updated to reflect the
changes, and the stats will be bumped in a separate patch. The example
config will be updated in a separate patch due to more extensive
re-work.

In a follow-on patch a new tester will be introduced that uses the
MemChecker to implement true sharing.
2015-02-11 10:23:28 -05:00
Andreas Sandberg
550c318490 sim: Move the BaseTLB to src/arch/generic/
The TLB-related code is generally architecture dependent and should
live in the arch directory to signify that.

--HG--
rename : src/sim/BaseTLB.py => src/arch/generic/BaseTLB.py
rename : src/sim/tlb.cc => src/arch/generic/tlb.cc
rename : src/sim/tlb.hh => src/arch/generic/tlb.hh
2015-02-11 10:23:27 -05:00
Andreas Sandberg
9e6f803254 base: Add compiler macros to add deprecation warnings
Gcc and clang both provide an attribute that can be used to flag a
function as deprecated at compile time. This changeset adds a gem5
compiler macro for that compiler feature. The macro can be used to
indicate that a legacy API within gem5 has been deprecated and provide
a graceful migration to the new API.
2015-02-11 10:23:24 -05:00
Andreas Hansson
c9b8616c51 base: Do not dereference NULL in CompoundFlag creation
This patch fixes the CompoundFlag constructor, ensuring that it does
not dereference NULL. Doing so has undefined behaviuor, and both clang
and gcc's undefined-behaviour sanitiser was rather unhappy.
2015-02-11 10:23:23 -05:00
Andreas Sandberg
431a6d708b dev: Remove unused system pointer in the Platform base class
The Platform base class contains a pointer to an instance of the
System which is never initialized. This can lead to subtle bugs since
some architecture-specific platform implementations contain their own
system pointer which is normally used. However, if the platform is
accessed through a pointer to its base class, the dangling pointer
will be used instead.
2015-02-11 10:23:22 -05:00
Alexandru Dutu
ad1b177550 cpu: Idle CPU status logic revised
This patch sets the CPU status to idle when the last active thread gets
suspended.
2015-02-06 18:01:22 -08:00
Andreas Hansson
461a80beb3 mem: Clarify express snoop behaviour
This patch adds a bit of documentation with insights around how
express snoops really work.
2015-02-03 14:26:02 -05:00
Andreas Hansson
193325ff60 mem: Clarify cache behaviour for pending dirty responses
This patch adds a bit of clarification around the assumptions made in
the cache when packets are sent out, and dirty responses are
pending. As part of the change, the marking of an MSHR as in service
is simplified slightly, and comments are added to explain what
assumptions are made.
2015-02-03 14:25:59 -05:00
Curtis Dunham
f0a764edc6 base: add an accessor and operators ==,!= to address ranges 2015-02-03 14:25:58 -05:00
Andreas Hansson
ccb512ecc1 base: Add XOR-based hashed address interleaving
This patch extends the current address interleaving with basic hashing
support. Instead of directly comparing a number of address bits with a
matching value, it is now possible to use two independent set of
address bits XOR'ed together. This avoids issues where strided address
patterns are heavily biased to a subset of the interleaved ranges.
2015-02-03 14:25:54 -05:00
Andreas Hansson
5ea60a95b3 config: Adjust DRAM channel interleaving defaults
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.
2015-02-03 14:25:52 -05:00
Andreas Sandberg
fe200c2487 sim: Remove test for non-NULL this in Event
The method Event::initialized() tests if this != NULL as a part of the
expression that tests if an event is initialized. The only case when
this check could be false is if the method is called on a null
pointer, which is illegal and leads to undefined behavior (such as
eating your pets) according to the C++ standard. Because of this,
modern compilers (specifically, recent versions of clang) warn about
this which we treat as an error. This changeset removes the redundant
check to fix said warning.
2015-02-03 14:25:48 -05:00
Andreas Sandberg
851b29ad20 dev: Correctly clear interrupts in VirtIO PCI
Correctly clear the PCI interrupt belonging to a VirtIO device when
the ISR register is read.
2015-02-03 14:25:47 -05:00
Curtis Dunham
b89fd57663 sim: prioritize async events; prevent starvation
If a time quantum event is the only one in the queue, async
events (Ctrl-C, I/O, etc.) will never be processed.

So process them first.
2014-12-19 15:32:34 -06:00
Andreas Hansson
20111ba917 cpu: Ensure timing CPU sinks response before sending new request
This patch changes how the timing CPU deals with processing responses,
always scheduling an event, even if it is for the current tick. This
helps to avoid situations where a new request shows up before a
response is finished in the crossbar, and also is more in line with
any realistic behaviour.
2015-02-03 14:25:27 -05:00
Geoffrey Blake
3e33786db8 config: Fix typo in Float param
The Float param was not settable on the command line
due to a typo in the class definition in
python/m5/params.py.  This corrects the typo and allows
floats to be set on the command line as intended.
2015-02-03 14:25:07 -05:00
Ali Saidi
89b3616d7e arm: always set the IsFirstMicroop flag
While the IsFirstMicroop flag exists it was only occasionally used in the ARM
instructions that gem5 microOps and therefore couldn't be relied on to be correct.
2015-01-25 07:22:56 -05:00
Ali Saidi
9d8ddd92dc sim: Clean up InstRecord
Track memory size and flags as well as add some comments and consts.
2015-01-25 07:22:44 -05:00
Ali Saidi
f6742ea26e cpu: Remove all notion that we know when the cpu is misspeculating.
We have no way of knowing if a CPU model is on the wrong path with
our execute-in-execute CPU models. Don't pretend that we do.
2015-01-25 07:22:26 -05:00
Ali Saidi
0bd986015b cpu: Put all CPU instruction tracers in a single file 2015-01-25 07:22:17 -05:00
Ali Saidi
6c4a23c1c6 cpu: remove legion tracer
If someone wants to debug with legion again they can restore the
code from the repository, but no need to have it hang around indefinately.
2015-01-25 07:22:05 -05:00
Curtis Dunham
10b5e5431d sim: fix reference counting of PythonEvent
When gem5 is a slave to another simulator and the Python is only used
to initialize the configuration (and not perform actual simulation), a
"debug start" (--debug-start) event will get freed during or immediately
after the initial Python frame's execution rather than remaining in the
event queue. This tricky patch fixes the GC issue causing this.
2014-12-23 11:51:40 -06:00
Andreas Hansson
10c69bb168 mem: Remove unused Packet src and dest fields
This patch takes the final step in removing the src and dest fields in
the packet. These fields were rather confusing in that they only
remember a single multiplexing component, and pushed the
responsibility to the bridge and caches to store the fields in a
senderstate, thus effectively creating a stack. With the recent
changes to the crossbar response routing the crossbar is now
responsible without relying on the packet fields. Thus, these
variables are now unused and can be removed.
2015-01-22 05:01:31 -05:00
Andreas Hansson
15c64035ed mem: Remove Packet source from ForwardResponseRecord
This patch removes the source field from the ForwardResponseRecord,
but keeps the class as it is part of how the cache identifies
responses to hardware prefetches that are snooped upwards.
2015-01-22 05:01:30 -05:00
Andreas Hansson
0c2ffd2daa mem: Remove unused RequestState in the bridge
This patch removes the bridge sender state as the Crossbar now takes
care of remembering its own routing decisions.
2015-01-22 05:01:27 -05:00
Andreas Hansson
00536b0efc mem: Always use SenderState for response routing in RubyPort
This patch aligns how the response routing is done in the RubyPort,
using the SenderState for both memory and I/O accesses. Before this
patch, only the I/O used the SenderState, whereas the memory accesses
relied on the src field in the packet. With this patch we shift to
using SenderState in both cases, thus not relying on the src field any
longer.
2015-01-22 05:01:24 -05:00
Andreas Hansson
072f78471d mem: Make the XBar responsible for tracking response routing
This patch removes the need for a source and destination field in the
packet by shifting the onus of the tracking to the crossbar, much like
a real implementation. This change in behaviour also means we no
longer need a SenderState to remember the source/dest when ever we
have multiple crossbars in the system. Thus, the stack that was
created by the SenderState is not needed, and each crossbar locally
tracks the response routing.

The fields in the packet are still left behind as the RubyPort (which
also acts as a crossbar) does routing based on them. In the succeeding
patches the uses of the src and dest field will be removed. Combined,
these patches improve the simulation performance by roughly 2%.
2015-01-22 05:01:14 -05:00
Andreas Hansson
ce12d4bc63 x86: Delay X86 table walk on receiving walker response
This patch fixes a minor issue in the X86 page table walker where it
ended up sending new request packets to the crossbar before the
response processing was finished (recvTimingResp is directly calling
sendTimingReq). Under certain conditions this caused the crossbar to
see illegal combinations of request/response overlap, in turn causing
problems with a slightly modified crossbar implementation.
2015-01-22 05:00:54 -05:00
Andreas Hansson
f49830ce0b mem: Clean up Request initialisation
This patch tidies up how we create and set the fields of a Request. In
essence it tries to use the constructor where possible (as opposed to
setPhys and setVirt), thus avoiding spreading the information across a
number of locations. In fact, setPhys is made private as part of this
patch, and a number of places where we callede setVirt instead uses
the appropriate constructor.
2015-01-22 05:00:53 -05:00
Nikos Nikoleris
a35283ac65 cpu: commit probe notification on every microop or macroop
The ppCommit should notify the attached listener every time the cpu commits
a microop or non microcoded insturction. The listener can then decide
whether it will process only the last microop (eg. SimPoint probe).

Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2015-01-20 14:15:27 -06:00
Andreas Hansson
6096e2f9c1 mem: Fix bug in cache request retry mechanism
This patch ensures that inhibited packets that are about to be turned
into express snoops do not update the retry flag in the cache.
2015-01-20 08:12:01 -05:00
Andreas Hansson
da0c770943 cpu: Fix retry bug in MinorCPU LSQ 2015-01-20 08:11:58 -05:00
Andreas Hansson
92585d60c9 mem: Move DRAM interleaving check to init
This patch fixes a bug where the DRAM controller tried to access the
system cacheline size before the system pointer was initialised. It
also fixes a bug where the granularity is 0 (no interleaving).
2015-01-20 08:11:55 -05:00
Emilio Castillo
7bb65dd434 x86 : fxsave and fxrestore missing template code
This patch corrects the FXSAVE and FXRSTOR Macroops.  The actual code used for
saving/restore the FP registers is in the file but it was not used.

The FXSAVE and FXRSTOR instructions are used in the kernel for saving and
loading the state of the mmx,xmm and fpu registers.

This operation is triggered in FS by issuing a Device Not Available Fault.  The
cr0 register has a TS flag that is set upon each context change. Every time a
task access any FP related register (SIMD as well) if the TS flag is set to
one, the device not available fault is issued.  The kernel saves the current
state of the registers, and restore the previous state of the currently running
task.

Right now Gem5 lacks of this capability. the Device Not Available Fault is
never issued, leading to several problems when different threads share the same
CPU and SMT is not used. The PARSEC Ferret benchmark is an example of this
behavior.

In order to test this a hack in the atomic cpu code was done to detect if a
static instruction has any FP operands and the cr0 reg TS bit is set.  This
check must be done in the ISA dependent code. But it seems to be tricky to
access the cr0 register while executing an instruction.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2015-01-10 14:30:53 -06:00
Nikos Nikoleris
ec64b81a9d cpu: fix RetiredStores probe point
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2015-01-10 14:30:53 -06:00
cdirik
1693e526d0 dev: prevent intel 8254 timer counter events firing before startup
This change includes edits to Intel8254Timer to prevent counter events firing
before startup to comply with SimObject initialization call sequence.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2015-01-06 15:10:22 -07:00
Gabe Black
1c1fb2c988 test: Add a unittest for the BitUnion types. 2015-01-07 00:34:40 -08:00
Gabe Black
86dea86987 base: Fix assigning between identical bitfields.
If two bitfields are of the same type, also implying that they have the same
first and last bit positions, the existing implementation would copy the
entire bitfield. That includes the __data member which is shared among all the
bitfields, effectively overwritting the entire bitunion.

This change also adjusts the write only signed bitfield assignment operator to
be like the unsigned version, using "using" instead of implementing it again
and calling down to the underlying implementation.
2015-01-07 00:31:46 -08:00
Gabe Black
cd6380605c x86: Enable three bits in the FamilyModelStepping ECX CPUID bitfield.
These are for the monitor/mwait instructions, SSSE3, and XSAVE.
2015-01-06 22:15:00 -08:00
Gabe Black
cb181d6f91 cpuid, x86: Revert "Enabling more features in CPUid"
That change enables CPUID bits for features that aren't implemented in gem5.
If a simulated system tries to use those features because it was told it
could, bad things can happen.
2015-01-06 22:13:56 -08:00
Andrew Lukefahr
6d32004407 minor: fixed LSQ MasterPortID
Minor was reporting the data cache access as ".inst" accesses.
This just switches the MasterPortID to dataMasterPortId.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2015-01-03 17:51:48 -06:00
mike upton
cb911559dc arm: Add unlinkat syscall implementation
added ARM aarch64 unlinkat syscall support, modeled on other <xxx>at syscalls.
This gets all of the cpu2006 int workloads passing in SE mode on aarch64.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2015-01-03 17:51:48 -06:00
Maxime Martinasso
5a5416d575 x86: implements the simd128 ADDSUBPD instruction
This patch implements the simd128 ADDSUBPD instruction for the x86 architecture.

Tested with a simple program in assembly language which executes the
instruction.  Checked that different versions of the instruction are executed
by using the execution tracing option.

Committed by: Nilay Vaish <nilay@cs.wisc.edu
2015-01-03 17:51:48 -06:00
Cagdas Dirik
02c376ac44 dev: prevent RTC events firing before startup
This change includes edits to MC146818 timer to prevent RTC events
firing before startup to comply with SimObject initialization call sequence.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2015-01-03 17:51:48 -06:00
Joel Hestness
642b9b4fab syscall_emul: Return correct writev value
According to Linux man pages, if writev is successful, it returns the total
number of bytes written. Otherwise, it returns an error code. Instead of
returning 0, return the result from the actual call to writev in the system
call.
2014-12-27 13:48:40 -06:00
Mitch Hayenga
b2342c5d9a mem: Change prefetcher to use random_mt
Prefechers has used rand() to generate random numers previously.
2014-12-23 09:31:19 -05:00
Curtis Dunham
516e6046ae mem: Hide WriteInvalidate requests from prefetchers
Without this tweak, a prefetcher will happily prefetch data that will
promptly be invalidated and overwritten by a WriteInvalidate.
2014-12-23 09:31:19 -05:00
Mitch Hayenga
bd4f901c77 mem: Fix event scheduling issue for prefetches
The cache's MemSidePacketQueue schedules a sendEvent based upon
nextMSHRReadyTime() which is the time when the next MSHR is ready or whenever
a future prefetch is ready.  However, a prefetch being ready does not guarentee
that it can obtain an MSHR.  So, when all MSHRs are full,
the simulation ends up unnecessiciarly scheduling a sendEvent every picosecond
until an MSHR is finally freed and the prefetch can happen.

This patch fixes this by not signaling the prefetch ready time if the prefetch
could not be generated.  The event is rescheduled as soon as a MSHR becomes
available.
2014-12-23 09:31:18 -05:00
Mitch Hayenga
4acd4a2055 mem: Fix bug relating to writebacks and prefetches
Previously the code commented about an unhandled case where it might be
possible for a writeback to arrive after a prefetch was generated but
before it was sent to the memory system.  I hit that case.  Luckily
the prefetchSquash() logic already in the code handles dropping prefetch
request in certian circumstances.
2014-12-23 09:31:18 -05:00
Mitch Hayenga
df82a2d003 mem: Rework the structuring of the prefetchers
Re-organizes the prefetcher class structure. Previously the
BasePrefetcher forced multiple assumptions on the prefetchers that
inherited from it. This patch makes the BasePrefetcher class truly
representative of base functionality. For example, the base class no
longer enforces FIFO order. Instead, prefetchers with FIFO requests
(like the existing stride and tagged prefetchers) now inherit from a
new QueuedPrefetcher base class.

Finally, the stride-based prefetcher now assumes a custimizable lookup table
(sets/ways) rather than the previous fully associative structure.
2014-12-23 09:31:18 -05:00
Mitch Hayenga
6cb58b2bd2 mem: Add parameter to reserve MSHR entries for demand access
Adds a new parameter that reserves some number of MSHR entries for demand
accesses.  This helps prevent prefetchers from taking all MSHRs, forcing demand
requests from the CPU to stall.
2014-12-23 09:31:18 -05:00
Curtis Dunham
4d88978913 arm: Add stats to table walker
This patch adds table walker stats for:
- Walk events
- Instruction vs Data
- Page size histogram
- Wait time and service time histograms
- Pending requests histogram (per cycle) - measures dist. of L
  (p(1..) = how often busy, p(0) = how often idle)
- Squashes, before starting and after completion
2014-12-23 09:31:18 -05:00
Andreas Hansson
59460b91f3 config: Expose the DRAM ranks as a command-line option
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).
2014-12-23 09:31:18 -05:00
Andreas Hansson
2f7baf9dbe mem: Ensure DRAM controller is idle when in atomic mode
This patch addresses an issue seen with the KVM CPU where the refresh
events scheduled by the DRAM controller forces the simulator to switch
out of the KVM mode, thus killing performance.

The current patch works around the fact that we currently have no
proper API to inform a SimObject of the mode switches. Instead we rely
on drainResume being called after any switch, and cache the previous
mode locally to be able to decide on appropriate actions.

The switcheroo regression require a minor stats bump as a result.
2014-12-23 09:31:18 -05:00
Omar Naji
381d1da791 mem: Add rank-wise refresh to the DRAM controller
This patch adds rank-wise refresh to the controller, as opposed to the
channel-wide refresh currently in place. In essence each rank can be
refreshed independently, and for this to be possible the controller
is extended with a state machine per rank.

Without this patch the data bus is always idle during a refresh, as
all the ranks are refreshing at the same time. With the rank-wise
refresh it is possible to use one rank while another one is
refreshing, and thus the data bus can be kept busy.

The patch introduces a Rank class to encapsulate the state per rank,
and also shifts all the relevant banks, activation tracking etc to the
rank. The arbitration is also updated to consider the state of the rank.
2014-12-23 09:31:18 -05:00
Omar Naji
152c02354e mem: Fix a bug in the DRAM controller arbitration
Fix a minor issue that affects multi-rank systems.
2014-12-23 09:31:18 -05:00
Kanishk Sugand
7a25b1a0e0 mem: Add stack distance statistics to the CommMonitor
This patch adds the stack distance calculator to the CommMonitor. The
stats are disabled by default.
2014-12-23 09:31:18 -05:00
Kanishk Sugand
888975b29d mem: Add a stack distance calculator
This patch adds a stand-alone stack distance calculator. The stack
distance calculator is a passive SimObject that observes the addresses
passed to it. It calculates stack distances (LRU Distances) of
incoming addresses based on the partial sum hierarchy tree algorithm
described by Alamasi et al. http://doi.acm.org/10.1145/773039.773043.

For each transaction a hashtable look-up is performed. At every
non-unique transaction the tree is traversed from the leaf at the
returned index to the root, the old node is deleted from the tree, and
the sums (to the right) are collected and decremented. The collected
sum represets the stack distance of the found node. At every unique
transaction the stack distance is returned as
numeric_limits<uint64>::max().

In addition to the basic stack distance calculation, a feature to mark
an old node in the tree is added. This is useful if it is required to
see the reuse pattern. For example, Writebacks to the lower level
(e.g. membus from L2), can be marked instead of being removed from the
stack (isMarked flag of Node set to True). And then later if this same
address is accessed (by L1), the value of the isMarked flag would be
True. This gives some insight on how the Writeback policy of the
lower level affect the read/write accesses in an application.

Debugging is enabled by setting the verify flag to true. Debugging is
implemented using a dummy stack that behaves in a naive way, using STL
vectors. Note that this has a large impact on run time.
2014-12-23 09:31:18 -05:00
Marco Elver
dd0f3943e2 mem: Add MemChecker and MemCheckerMonitor
This patch adds the MemChecker and MemCheckerMonitor classes. While
MemChecker can be integrated anywhere in the system and is independent,
the most convenient usage is through the MemCheckerMonitor -- this
however, puts limitations on where the MemChecker is able to observe
read/write transactions.
2014-12-23 09:31:17 -05:00
Andreas Sandberg
184fefbb3b arm: Raise an alignment fault if a PC has illegal alignment
We currently don't handle unaligned PCs correctly. There is one check
for unaligned PCs in the TLB when running in aarch64 mode, but this
check does not cover cases where the CPU does not do a TLB lookup when
decoding an instruction (e.g., a branch stays within the same cache
line). Additionally, the Decoder class sometimes throws an assertion
for unaligned PCs which breaks speculation.

This changeset introduces a decoder fault bit field in the ExtMachInst
structure. This field can be used to signal a decoder failure. If set,
the decoder generates an internal gem5fault instruction instead of a
normal instruction. This instruction in turns either panics (fault
type PANIC), returns an PCAlignmentFault (fault type UNALIGNED,
aarch64) or PrefetchAbort (fault type UNALIGNED, aarch32).

The patch causes minor changes to the realview64 regressions, and a
stats bump will follow.
2014-12-23 09:31:17 -05:00
Andreas Sandberg
b33812ba43 arm: Clean up and document decoder API
This changeset adds more documentation to the ArmISA::Decoder class
and restructures it slightly to make API groups more obvious.
2014-12-23 09:31:17 -05:00