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.
This member indicates whether or not a particular virtual network is in use.
Instead of having a default big value for the number of virtual networks and
then checking whether a virtual network is in use, the next patch removes the
default value and the protocol configuration file would now specify the
number of virtual networks it requires.
Additionally, the patch also refactors some of the code used for computing the
virtual channel next in the round robin order.
Both FuncCallExprAST and MethodCallExprAST had code for checking the arguments
with which a function is being called. The patch does away with this
duplication. Now the code for checking function call arguments resides in the
Func class.
The new serialization code (kudos to Tim Jones) moves all of the state
mangling in RubySystem to memWriteback. This makes it possible to use
the new const serialization interface.
This changeset moves the cache recorder cleanup from the checkpoint()
method to drainResume() to make checkpointing truly constant and
updates the checkpointing code to use the new interface.
The sequencer takes care of llsc accesses by calling upon functions
from the CacheMemory. This is unnecessary once the required CacheEntry object
is available. Thus some of the calls to findTagInSet() are avoided.
The O3CPU blocks the Fetch when it sees a quiesce instruction (IsQuiesce flag).
When the inst. is executed, a quiesce event is created to reactivate the
context and unblock the Fetch.
If the quiesceNs or quiesceCycles are called with a value of 0, the
QuiesceEvent will not be created and the Fetch stage will remain blocked.
Committed by Joel Hestness <jthestness@gmail.com>
This patch reverts part of (842f56345a42), as apparently there are
use-cases outside the main repository relying on the late setting of
the physical address.
This patch simplifies the packet, and removes the possibility of
creating a packet without a valid address and/or size. Under no
circumstances are these fields set at a later point, and thus they
really have to be provided at construction time.
The patch also fixes a case there the MinorCPU creates a packet
without a valid address and size, only to later delete it.
Cleaning up dead code. The CLREX stores zero directly to
MISCREG_LOCKFLAG and so the request flag is no longer needed. The
corresponding functionality in the cache tags is also removed.
Open up for other subclasses to BaseCache and transition to using the
explicit Cache subclass.
--HG--
rename : src/mem/cache/BaseCache.py => src/mem/cache/Cache.py
This patch serves to avoid name clashes with the classic cache. For
some reason having two 'SimObject' files with the same name creates
problems.
--HG--
rename : src/mem/ruby/structures/Cache.py => src/mem/ruby/structures/RubyCache.py
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.
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.
