Instead of conservatively enforcing order for all packets, which may
negatively impact the simulated-system performance, this patch updates
the packet queue such that it only applies the restriction if there
are already packets with the same address in the queue.
The basic need for the order enforcement is due to coherency
interactions where requests/responses to the same cache line must not
over-take each other. We rely on the fact that any packet that needs
order enforcement will have a block-aligned address. Thus, there is no
need for the queue to know about the cacheline size.
This patch enforces insertion order transmission of packets on the
response path in the cache. Note that the logic to enforce order is
already present in the packet queue, this patch simply turns it on for
queues in the response path.
Without this patch, there are corner cases where a request-response is
faster than a response-response forwarded through the cache. This
violation of queuing order causes problems in the snoop filter leaving
it with inaccurate information. This causes assert failures in the
snoop filter later on.
A follow on patch relaxes the order enforcement in the packet queue to
limit the performance impact.
This patch updates the I/O devices, bridge and simple memory to take
the packet header and payload delay into account in their latency
calculations. In all cases we add the header delay, i.e. the
accumulated pipeline delay of any crossbars, and the payload delay
needed for deserialisation of any payload.
Due to the additional unknown latency contribution, the packet queue
of the simple memory is changed to use insertion sorting based on the
time stamp. Moreover, since the memory hands out exclusive (non
shared) responses, we also need to ensure ordering for reads to the
same address.
This patch aligns how the memory-system slaves, i.e. the various
memory controllers and the bridge, identify and deal with sinking of
inhibited packets that are only useful within the coherent part of the
memory system.
In the future we could shift the onus to the crossbar, and add a
parameter "is_point_of_coherence" that would allow it to sink the
aforementioned packets.
This patch changes the CleanEvict command type to not be considered a
write. Initially it was made a zero-sized write to match the writeback
command, but as things developed it became clear that it causes more
problems than it solves. For example, the memory modules (and bridge)
should not consider the CleanEvict as a write, but instead discard
it. With this patch it will be neither a read, nor write, and as it
does not need a response the slave will simply sink it.
This patch unifies how we deal with delayed packet deletion, where the
receiving slave is responsible for deleting the packet, but the
sending agent (e.g. a cache) is still relying on the pointer until the
call to sendTimingReq completes. Previously we used a mix of a
deletion vector and a construct using unique_ptr. With this patch we
ensure all slaves use the latter approach.
The CoherentXBar currently doesn't check its queued slave ports when
receiving a functional snoop. This caused data corruption in cases
when a modified cache lines is forwarded between two caches.
Add the required functional calls into the queued slave ports.
This changeset adds a serial link model for the Hybrid Memory Cube (HMC).
SerialLink is a simple variation of the Bridge class, with the ability to
account for the latency of packet serialization. Also trySendTiming has been
modified to correctly model bandwidth.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch models a simple HMC Controller. It simply schedules the incoming
packets to HMC Serial Links using a round robin mechanism. This patch should
be applied in series with other patches modeling a complete HMC device.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch enables modeling a complete Hybrid Memory Cube (HMC) device. It
highly reuses the existing components in gem5's general memory system with some
small modifications. This changeset requires additional patches to model a
complete HMC device.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
makeSparcSystem() in configs/common/FSConfig.py is missing the cmdLine
parameter Without the parameter the simulation fails to start. With the
parameter the simulation starts properly.
Fix a bug in which the flash device would write out of bounds and
could either trigger a segfault and corrupt the memory of other
objects. This was caused by using pageSize in the place of
pagesPerBlock when running the garbage collector.
Also, added an assert to flag this condition in the future.
This patch fixes the drain logic for the UFSHostDevice and the
FlashDevice. In the case of the FlashDevice, the logic for CheckDrain
needed to be reversed, whilst in the case of the UFSHostDevice check
drain was never being called. In both cases the system would never
complete draining if the initial attampt to drain failed.
This patch addresses the upgrading of deferred targets in the MSHR,
and makes it clearer by explicitly calling out what is happening
(deferred targets are promoted if we get exclusivity without asking
for it).
This patch adds explicit overrides as this is now required when using
"-Wall" with clang >= 3.5, the latter now part of the most recent
XCode. The patch consequently removes "virtual" for those methods
where "override" is added. The latter should be enough of an
indication.
As part of this patch, a few minor issues that clang >= 3.5 complains
about are also resolved (unused methods and variables).
This patch moves away from using M5_ATTR_OVERRIDE and the m5::hashmap
(and similar) abstractions, as these are no longer needed with gcc 4.7
and clang 3.1 as minimum compiler versions.
ARM uses UDelayEvents to emulate kernel __*udelay functions and speed up
simulation. UDelayEvents call Pseudoinst::quiesceNs to quiesce the system for
a specified delay. Changeset 10341:0b4d10f53c2d introduced the requirement
that any quiesce process that is started must also be completed by scheduling
an EndQuiesceEvent. This change causes the CPU to hang if an IsQuiesce
instruction is executed, but the corresponding EndQuiesceEvent is not
scheduled.
Changeset 11058:d0934b57735a introduces a fix for uses of PseudoInst::quiesce*
that would conditionally execute the EndQuiesceEvent. ARM UDelayEvents specify
quiesce period of 0 ns (src/arch/arm/linux/system.cc), so changeset 11058
causes these events to now execute full quiesce processes, greatly increasing
the total instructions executed in kernel delay loops and slowing simulation.
This patch updates the UDelayEvent to conditionally execute
PseudoInst::quiesceNs (**a quiesce operation**) only if the specified
delay is >0 ns. The result is ARM delay loops no longer execute instructions
for quiesce handling, and regression time returns to normal.
The decoder is responsible for splitting instructions in micro
operations (uops). Given that different micro architectures may split
operations differently, this patch allows to specify which micro
architecture each isa implements, so different cores in the system can
split instructions differently, also decoupling uop splitting
(microArch) from ISA (Arch). This is done making the decodification
calls templates that receive a type 'DecoderFlavour' that maps the
name of the operation to the class that implements it. This way there
is only one selection point (converting the command line enum to the
appropriate DecodeFeatures object). In addition, there is no explicit
code replication: template instantiation hides that, and the compiler
should be able to resolve a number of things at compile-time.
Although some decent error messages were getting generated inside
isa_parser.py, they weren't always getting printed because of the
screwy way we were handling exceptions. (Basically an inner
exception would get hidden by an outer exception, and the more
informative inner error message would not get printed.)
Also line numbers were messed up, since they were taken from the
lexer, which is typically a token (or more) ahead of the grammar
rule that's being matched. Using the 'lineno' attribute that
PLY associates with the grammar production is more accurate.
The new LineTracker class extends lineno to track filenames as
well as line numbers.
This information is useful if you have a bunch of simulations running
and want to know which one to kill, but you've neglected to take
advantage of the previous patch and embed the pid in your output path.
These are packed single-precision approximate reciprocal operations,
vector and scalar versions, respectively.
This code was basically developed by copying the code for
sqrtps and sqrtss. The mrcp micro-op was simplified relative to
msqrt since there are no double-precision versions of this operation.
fild loads an integer value into the x87 top of stack register.
fucomi/fucomip compare two x87 register values (the latter
also doing a stack pop).
These instructions are used by some versions of GNU libstdc++.
The renamings in changesets 8f5993cf (2015-03-23) "mem: rename
Locked/LOCKED to LockedRMW/LOCKED_RMW" and fdd4a895 (2015-07-03)
"mem: Split WriteInvalidateReq into write and invalidate" broke the
SST connector. This commit repeats those renamings in ext/sst.
The 01.hello-2T-smt test case for the O3 CPU didn't correctly setup
the number of threads before creating interrupt controllers, which
confused the constructor in BaseCPU. This changeset adds SMT support
to the test configuration infrastructure.
--HG--
rename : tests/configs/o3-timing.py => tests/configs/o3-timing-mt.py
rename : tests/quick/se/01.hello-2T-smt/ref/alpha/linux/o3-timing/config.ini => tests/quick/se/01.hello-2T-smt/ref/alpha/linux/o3-timing-mt/config.ini
rename : tests/quick/se/01.hello-2T-smt/ref/alpha/linux/o3-timing/simerr => tests/quick/se/01.hello-2T-smt/ref/alpha/linux/o3-timing-mt/simerr
rename : tests/quick/se/01.hello-2T-smt/ref/alpha/linux/o3-timing/simout => tests/quick/se/01.hello-2T-smt/ref/alpha/linux/o3-timing-mt/simout
rename : tests/quick/se/01.hello-2T-smt/ref/alpha/linux/o3-timing/stats.txt => tests/quick/se/01.hello-2T-smt/ref/alpha/linux/o3-timing-mt/stats.txt
The DTRACE() macro tests both Trace::enabled and the specific flag. This
change uses the same administrative interface for enabling/disabling
tracing, but masks the SimpleFlags settings directly. This eliminates a
load for every DTRACE() test, e.g. DPRINTF.
In ARM, certain variables are only updated when a necessary change is
detected. Having 2 SMT threads share a TLB resulted in these not being
updated as required. This patch adds a thread context identifer to
assist in the invalidation of these variables.
Adds SMT support to the "simple" CPU models so that they can be
used with other SMT-supported CPUs. Example usage: this enables
the TimingSimpleCPU to be used to warmup caches before swapping to
detailed mode with the in-order or out-of-order based CPU models.
Trying to run an SE system with varying threads per core (SMT cores + Non-SMT
cores) caused failures due to the CPU id assignment logic. The comment
about thread assignment (worrying about core 0 not having tid 0) seems
not to be valid given that our configuration scripts initialize them in
order.
This removes that constraint so a heterogenously threaded sytem can work.
