Some blocks in MOESI hammer were not getting deallocated when they were set to
an idle state (e.g. by invalidate or other_getx/s messages). While
functionally correct, this caused some bad effects on performance, such as
blocks in I in the L1s getting sent to the L2 upon eviction, in turn evicting
valid blocks. Also, if a valid block was in LRU, that block could be evicted
rather than a block in I. This patch adds in the missing deallocations.
Committed by: Nilay Vaish<nilay@cs.wisc.edu>
The recent changes to make MessageBuffers SimObjects required them to be
initialized in a particular order, which could break some protocols. Fix this
by calling initNetQueues on the external nodes of each external link in the
constructor of Network.
This patch also refactors the duplicated code for checking network allocation
and setting net queues (which are called by initNetQueues) from the simple and
garnet networks to be in Network.
This patch changes MessageBuffer and TimerTable, two structures used for
buffering messages by components in ruby. These structures would no longer
maintain pointers to clock objects. Functions in these structures have been
changed to take as input current time in Tick. Similarly, these structures
will not operate on Cycle valued latencies for different operations. The
corresponding functions would need to be provided with these latencies by
components invoking the relevant functions. These latencies should also be
in Ticks.
I felt the need for these changes while trying to speed up ruby. The ultimate
aim is to eliminate Consumer class and replace it with an EventManager object in
the MessageBuffer and TimerTable classes. This object would be used for
scheduling events. The event itself would contain information on the object and
function to be invoked.
In hindsight, it seems I should have done this while I was moving away from use
of a single global clock in the memory system. That change led to introduction
of clock objects that replaced the global clock object. It never crossed my
mind that having clock object pointers is not a good design. And now I really
don't like the fact that we have separate consumer, receiver and sender
pointers in message buffers.
The eventual aim of this change is to pass RubySystem pointers through to
objects generated from the SLICC protocol code.
Because some of these objects need to dereference their RubySystem pointers,
they need access to the System.hh header file.
In src/mem/ruby/SConscript, the MakeInclude function creates single-line header
files in the build directory that do nothing except include the corresponding
header file from the source tree.
However, SLICC also generates a list of header files from its symbol table, and
writes it to mem/protocol/Types.hh in the build directory. This code assumes
that the header file name is the same as the class name.
The end result of this is the many of the generated slicc files try to include
RubySystem.hh, when the file they really need is System.hh. The path of least
resistence is just to rename System.hh to RubySystem.hh.
--HG--
rename : src/mem/ruby/system/System.cc => src/mem/ruby/system/RubySystem.cc
rename : src/mem/ruby/system/System.hh => src/mem/ruby/system/RubySystem.hh
These tests will ensure that Learning gem5 scripts are always up to date with
the changes in the mainline of gem5.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
Added a new directory in configs (learning_gem5) to hold the scripts that are
used in the book. See http://lowepower.com/jason/learning_gem5/ for a working
copy. For now, only the scripts in Part 1: Getting started with gem5
have been added. A separate patch adds tests for these scripts.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This register is writable according to UA2005
Tried to boot NetBSD which starts the kernel by writing to the tick_cmpr
register. Without the patch gem5 crashes with a panic. With the patch NetBSD
starts to boot normally (although sun4v support in NetBSD is not complete yet)
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
Handle bad IDE disk image size 0. When image size is 0, gem5 will cause an
exception with log "Floating point exception (core dumped)".
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
If the terminal was used in the SystemC or TLM simulations the simulation gets
in a deadlock state. This is because of the Event queue gets locked while
servicing the async events leading to event queue deadlock. This was solved by
locking the queue at the beginning of service of async events.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
The CleanEvict command was not considered in /util/tlm/sc_port.cc this could
lead to a simulator crash. This issue is solved by ignoring this special
command type.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
When a branch gets squashed, it's speculative branch predictor state should get
rolled back in squash(). However, only the globalHistory state was being
rolled back. This patch adds (at least some) support for rolling back the
local predictor state also.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch enables instructions in LSQ to track two physical addresses for
corresponding two split requests. Later, the information is used in
checksnoop() to search for/invalidate the corresponding LD instructions.
The current implementation has kept track of only the physical address that is
referenced by the first split request. Thus, for checksnoop(), the line
accessed by the second request has not been considered, causing potential
correctness issues.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
Refactored the code in operateVnet(), moved partly to a new function
operateMessageBuffer(). This is required since a later patch moves to having a
wakeup event per MessageBuffer instead of one event for the entire Switch.
There are two reasons for doing so:
a. provide a source of clock to PerfectSwitch. A follow on patch removes sender
and receiver pointers from MessageBuffer means that the object owning the
buffer should have some way of providing timing info.
b. schedule events. A follow on patch removes the consumer class. So the
PerfectSwitch needs some EventManager object to schedule events on its own.
Add a stat that counts buffer underruns in the HDLCD controller. The
stat counts at most one underrun per frame since the controller aborts
the current frame if it underruns.
Rewrite the HDLCD controller to use the new DMA engine and pixel
pump. This fixes several bugs in the current implementation:
* Broken/missing interrupt support (VSync, underrun, DMA end)
* Fragile resolution changes (changing resolutions used
to cause assertion errors).
* Support for resolutions with a width that isn't divisible by 32.
* The pixel clock can now be set dynamically.
This breaks checkpoint compatibility. Checkpoints can be upgraded with
the checkpoint conversion script. However, upgraded checkpoints won't
contain the state of the current frame. That means that HDLCD
controllers restoring from a converted checkpoint immediately start
drawing a new frame (i.e, expect timing differences).
Currently the sequencer calls the function setMRU that updates the replacement
policy structures with the first level caches. While functionally this is
correct, the problem is that this requires calling findTagInSet() which is an
expensive function. This patch removes the calls to setMRU from the sequencer.
All controllers should now update the replacement policy on their own.
The set and the way index for a given cache entry can be found within the
AbstractCacheEntry structure. Use these indicies to update the replacement
policy structures.
The current Set data structure is slow and therefore is being reimplemented
using std::bitset. A maximum limit of 64 is being set on the number of
controllers of each type. This means that for simulating a system with more
controllers of a given type, one would need to change the value of the variable
NUMBER_BITS_PER_SET
MessageBuffer is a SimObject now. There were protocols that still declared
some of the message buffers are variables of the controller, but not as input
parameters. Special handling was required for these variables in the SLICC
compiler. This patch changes this. Now all message buffers are declared as
input parameters.
In cases where a newly added target does not have any upstream MSHR to
mark as downstreamPending, remember that nothing is marked. This
allows us to avoid attempting to find the MSHR as part of the clearing
of downstreamPending.
This commit addresses gem5 checkpoints' linear versioning bottleneck.
Since development is distributed across many private trees, there exists
a sort of 'race' for checkpoint version numbers: internally a checkpoint
version may be used but then resynchronizing with the external tree causes
a conflict on that version. This change replaces the linear version number
with a set of unique strings called tags. Now the only conflicts that can
arise are of tag names, where collisions are much easier to avoid.
The checkpoint upgrader (util/cpt_upgrader.py) upgrades the version
representation, as one would expect. Each tag version implements its
upgrader code in a python file in the util/cpt_upgraders directory
rather than adding a function to the upgrader script itself.
The version tags are stored in the 'Globals' section rather than 'root'
(as the version was previously) because 'Globals' gets unserialized
first and can provide a warning before any other unserialization errors
can occur.
This is in support of tag-based checkpoint versioning. It should be
possible to examine an optional parameter in a checkpoint during
unserialization and not have it throw a warning.
We no longer use the C library based random number generator: random().
Instead we use the C++ library provided rng. So setting the random seed for
the RubySystem class has no effect. Hence the variable and the corresponding
option are being dropped.
Event auto-serialization no longer in use and has been broken ever
since the introduction of PDES support almost two years
ago. Additionally, serializing the individual event queues is
undesirable since it exposes the thread structure of the
simulator. What this means in practice is that the number of threads
in the simulator must be the same when taking a checkpoint and when
loading the checkpoint.
This changeset removes support for the AutoSerialize event flag and
the associated serialization code.
EtherLink currently uses a fire-and-forget link delay event that
delays sending of packets by a fixed number of ticks. In order to
serialize this event, it relies on the event queue's auto
serialization support. However, support for event auto serialization
has been broken for more than two years, which means that checkpoints
of multi-system setups are likely to drop in-flight packets.
This changeset the replaces rewrites this part of the EtherLink to use
a packet queue instead. The queue contains a (tick, packet) tuple. The
tick indicates when the packet will be ready. Instead of relying on
event autoserialization, we now explicitly serialize the packet queue
in the EhterLink::Link class.
Note that this changeset changes the way in-flight packages are
serialized. Old checkpoints will still load, but in-flight packets
will be dropped (just as before). There has been no attempt to upgrade
checkpoints since this would actually change the behavior of existing
checkpoints.
This changeset removes the support for the autoserialize parameter in
GlobalSimLoopExitEvent (including exitSimLoop()) and
LocalSimLoopExitEvent.
Auto-serialization of the LocalSimLoopExitEvent was never used, so
this is not expected to affect anything. However, it was sometimes
used for GlobalSimLoopExitEvent. Unfortunately, serialization of
global events has never been supported, so checkpoints with such
events will currently cause simulation panics.
The serialize parameter to exitSimLoop() has been left in-place to
maintain API compatibility (removing it would affect m5ops). Instead
of just dropping it, we now print a warning if the parameter is set
and the exit event is scheduled in the future (i.e., not at the
current tick).
The object resolver isn't serialization specific and shouldn't live in
serialize.hh. Move it to sim_object.hh since it queries to the
SimObject hierarchy.
