Gem5 Hardware Transactional Memory (HTM)
Here we provide a brief note describing HTM support in Gem5 at
a high level.
HTM is an architectural feature that enables speculative concurrency in
a shared-memory system; groups of instructions known as transactions are
executed as an atomic unit. The system allows that transactions be
executed concurrently but intervenes if a transaction's
atomicity/isolation is jeapordised and takes corrective action. In this
implementation, corrective active explicitely means rolling back a
thread's architectural state and reverting any memory updates to a point
just before the transaction began.
This HTM implementation relies on--
(1) A checkpointing mechanism for architectural register state.
(2) Buffering speculative memory updates.
This patch is focusing on the definition of the HTM checkpoint (1)
The checkpointing mechanism is architecture dependent. Each ISA
leveraging HTM support can define a class HTMCheckpoint inhereting from
the generic one (GenericISA::HTMCheckpoint).
Those will need to save/restore the architectural state by overriding
the virtual HTMCheckpoint::save (when starting a transaction) and
HTMCheckpoint::restore (when aborting a transaction).
Instances of this class live in O3's ThreadState and Atomic's
SimpleThread. It is up to the ISA to populate this instance when
executing an instruction that begins a new transaction.
JIRA: https://gem5.atlassian.net/browse/GEM5-587
Change-Id: Icd8d1913d23652d78fe89e930ab1e302eb52363d
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30314
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This class can already accept a proxy variable and a "functor" which is
a pointer to either a function or an instance of a class with the ()
operator overloaded.
This change adds a FunctorProxy partial specialization which accepts
anything that can be used to construct a std::function<Result()>. The
constructor argument is copied and stored in the proxy which makes it
possible to define a lambda inline without having to keep a copy of it
around for the proxy to point to.
Also, the ValueBase stat's functor method now has a second version which
accepts a const reference rather than just a reference to its argument.
We need both because when accepting a reference to a lambda it needs to
be a const reference, but when accepting a pointer to a functor object,
we don't want it to be const because that would force the () operator to
also be const.
Change-Id: Icb1b3682d51b721f6e16614490ed0fe289cee094
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32901
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
If the cxx_type value changes, then the way the parameter is declared
in the param struct will also change, and the header needs to be
updated. scons would miss this sort of change before because it was only
checking the module the SimObject's source came from. The python names
and types of the parameters could stay the same, but the C++
representation might have changed because of edits somewhere else.
This CL assumes that cxx_type is the only thing that will change and
transparently affect the params struct. I tried making scons sensitive
to the entire ptype which would capture other parameters, but that
didn't work for some reason. This should be pretty safe in general, but
not 100% safe
Issue-on: https://gem5.atlassian.net/browse/GEM5-753
Change-Id: I06774889e60b987f727799f55d7ea2a775b6a319
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33695
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This test, which measures the performance of cprintf vs. sprintf, was
missing a couple of includes which were needed for the alarm() and
signal() functions, as well as the SIGALRM constant.
Also, it was using %#x to print the value of a pointer which gcc
complained about when compiling sprintf. This is fixed by changing that
format specifier to %p, the specifier to use when printing pointers.
Apparently either the implicit conversion to an integer value (which %#x
expects) or the size of the type it was converted to weren't good enough
for gcc any more.
Change-Id: I8eca3479bef2c2fa79f8ef4881bb3ff35d7c54ca
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33897
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The "append" option of the Help() scons method can be used to avoid
clobbering the built in and local option help.
This has the nice side effect of making it easier to add options in
other files since you now only need the built in AddOption provided by
scons itself, not the custom AddLocalOption version.
Change-Id: Ifa566087797d578df0c90f8f4fca70c8152fbf63
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32115
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Gabe Black <gabeblack@google.com>
Allow all sub-compressors of BDI to be successful as long as
they are able to compress. Then, BDI's actual size threshold
acts as the cutting point.
This situation arises on any multi compressor; yet, generalizing
this assumption might be too bold.
Change-Id: Iec5057d16d4a7ba5fb573133a30ea10869bd67e0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33386
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The size can be zero in special occasions, which would
generate divisions by zero. This patch expands the
stats to support them. It also fixes the compression
factor calculation in the Multi compressor.
As a side effect, now that zero sizes are handled, allow
the Zero compressor to generate it.
Change-Id: I9f7dee76576b09fdc9bef3e1f3f89be3726dcbd9
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33383
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
When compressing using a multi-compressor, one must be able to
identify which sub-compressor should be used to decompress data.
This can be achieved by either adding encoding bits to block's
tag or data entry.
It was previously assumed that these encoding bits would be added
to the tag, but now make it a parameter that defaults to the data
entry.
Change-Id: Id322425e7a6ad59cb2ec7a4167a43de4c55c482c
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33380
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The compressors are not able to process a whole line at once,
so they must divide it into multiple same-sized chunks. This
patch makes the base compressor responsible for this division,
so that the derived classes are mostly agnostic to this
translation.
This change has been coupled with a change of the signature
of the public compress() to avoid introducing a temporary
function rename. Previously, this function did not return
the compressed data, under the assumption that everything
related to the compressed data would be handled by the
compressor. However, sometimes the units using the compressor
could need to know or store the compressed data.
For example, when sharing dictionaries the compressed data
must be checked to determine if two blocks can co-allocate
(DISH, Panda et al. 2016).
Change-Id: Id8dbf68936b1457ca8292cc0a852b0f0a2eeeb51
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33379
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Previously either the compression data was the one declared within
DictionaryCompressor, or the derived class would have to override
the compress() to use a derived compression data.
With this change, the instantiation can be overridden, and thus
any derived class can choose the compression data pointer type
they need to use.
Change-Id: I387936265a3de6785a6096c7a6bd21774202b1c7
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33378
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
When applying the bitwise not to a short integer the compiler
automatically promotes it to an integer. For example, if a 8-bit
mask=0xFF, and the compiler decides to promote the mask to 32-bit
to apply the bitwise not, ~mask=0xFFFFFF00, which will yield wrong
results for popcount(): expected=0, got=24.
Change-Id: I95efba5532c27ca004ff6947d4b51a8a14f09741
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33374
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
A new socket was created each time listen() is called,
which is problematic when the bind or listen operation
on it are not successful (mostly because the associated port is
already in use). It can lead gem5 to open too many files and crash
for multicores configurations, a socket being created
for remote GDB for each core. The other way to deal with
this problem would be to close the socket in the case the
function return false. But I find the proposed solution
simpler.
Change-Id: I848955a10c89e1da033bf773c83556a5dc5ef9a2
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32994
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
There was a missing option (--buffers-size) used to set the mandatory
queue size for the scalar controllers. This patch renames the option to
be more clear, and adds it to the argument parser.
Default of 128 taken from the implementation on the GCN staging branch
Change-Id: I58b6b57be07498cdf6e39c0bb85982674ec4caa6
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32676
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>
Tested-by: kokoro <noreply+kokoro@google.com>
db_offset used to be calculated through pointer arithmetic. Pointer
arithmetic increments the address by the size of the data type the
pointer is pointing at. In the previous db_offset calculation, that
was a uint32_t, which means the input was multiplied by 4, which is
sizeof(uint32_t)
This patch multiplies the input value by sizeof(uint32_t) before
assigning it to db_offset.
Change-Id: I9042560303ae6b8b1054b98e9a16a9da27843bb2
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32678
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Alexandru Duțu <alexandru.dutu@amd.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This change sets the properties in hsaTopology to the proper values
specified by the user through command-line arguments. This ensures
that if the properties file is read by a program, it will return
the correct values for the simulated hardware.
This change also adds in a command-line argument for the lds size, as
it was the only other property used in hsaTopology that didn't have
a command-line argument. The default value (65536) is taken from
src/gpu-compute/LdsState.py
Change-Id: I17bb812491708f4221c39b738c906f1ad944614d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/31995
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Alexandru Duțu <alexandru.dutu@amd.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>
Tested-by: kokoro <noreply+kokoro@google.com>
