offloading
- This patch adds support for thread_limit clause on target directive according to OpenMP 51 [2.14.5]
- The idea is to create an outer task for target region, when there is a thread_limit clause, and manipulate the thread_limit of task instead. This way, thread_limit will be applied to all the relevant constructs enclosed by the target region.
Differential Revision: https://reviews.llvm.org/D152054
This change adds the option of using different units for blocktimes specified via the KMP_BLOCKTIME environment variable. The parsing of the environment now recognizes units suffixes: ms and us. If a units suffix is not specified, the default unit is ms. Thus default behavior is still the same, and any previous usage still works the same. Internally, blocktime is now converted to microseconds everywhere, so settings that exceed INT_MAX in microseconds are considered "infinite".
kmp_set/get_blocktime are updated to use the units the user specified with KMP_BLOCKTIME, and if not specified, ms are used.
Added better range checking and inform messages for the two time units. Large values of blocktime for default (ms) case (beyond INT_MAX/1000) are no longer allowed, but will autocorrect with an INFORM message.
The delay for determining ticks per usec was lowered. It is now 1 million ticks which was calculated as ~450us based on 2.2GHz clock which is pretty typical base clock frequency on X86:
(1e6 Ticks) / (2.2e9 Ticks/sec) * (1e6 usec/sec) = 454 usec
Really short benchmarks can be affected by longer delay.
Update KMP_BLOCKTIME docs.
Portions of this commit were authored by Johnny Peyton.
Differential Revision: https://reviews.llvm.org/D157646
This patch implements the "__kmp_print_tdg_dot" function, that prints a task dependency graph into a dot file containing the tasks and their dependencies.
It is activated through a new environment variable "KMP_TDG_DOT"
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D150962
This patch implements the "task record and replay" mechanism. The idea is to be able to store tasks and their dependencies in the runtime so that we do not pay the cost of task creation and dependency resolution for future executions. The objective is to improve fine-grained task performance, both for those from "omp task" and "taskloop".
The entry point of the recording phase is __kmpc_start_record_task, and the end of record is triggered by __kmpc_end_record_task.
Tasks encapsulated between a record start and a record end are saved, meaning that the runtime stores their dependencies and structures, referred to as TDG, in order to replay them in subsequent executions. In these TDG replays, we start the execution by scheduling all root tasks (tasks that do not have input dependencies), and there will be no involvement of a hash table to track the dependencies, yet tasks do not need to be created again.
At the beginning of __kmpc_start_record_task, we must check if a TDG has already been recorded. If yes, the function returns 0 and starts to replay the TDG by calling __kmp_exec_tdg; if not, we start to record, and the function returns 1.
An integer uniquely identifies TDGs. Currently, this identifier needs to be incremented manually in the source code. Still, depending on how this feature would eventually be used in the library, the caller function must do it; also, the caller function needs to implement a mechanism to skip the associated region, according to the return value of __kmpc_start_record_task.
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D146642
Some globals were used for enforcing certain linking rules in the Intel
OpenMP implementation's MSVC compatibility layer and are not applicable
to the LLVM implementation (kmp_import.cpp has already been removed from
the build).
Differential Revision:https://reviews.llvm.org/D145837
ATOMIC_VAR_INIT has a trivial definition
`#define ATOMIC_VAR_INIT(value) (value)`,
is deprecated in C17/C++20, and will be removed in newer standards in
newer GCC/Clang (e.g. https://reviews.llvm.org/D144196).
Add new hidden helper affinity via the environment variable,
KMP_HIDDEN_HELPER_AFFINITY, which allows users to assign thread
affinity to hidden helper threads using the same syntax as
KMP_AFFINITY. OMP_PLACES/OMP_PROC_BIND have no interaction with
KMP_HIDDEN_HELPER_AFFINITY.
Differential Revision: https://reviews.llvm.org/D135113
This patch parameterizes the affinity initialization code to allow multiple
affinity settings. Almost all global affinity settings are consolidated
and put into a structure kmp_affinity_t. This is in anticipation of the
addition of hidden helper affinity which will have the same syntax and
semantics as KMP_AFFINITY only for the hidden helper team.
Differential Revision: https://reviews.llvm.org/D135109
Added control to reset affinity of primary thread after outermost parallel
region to initial affinity encountered before OpenMP runtime was initialized.
KMP_AFFINITY environment variable reset/noreset modifier introduced.
Default behavior is unchanged.
Differential Revision: https://reviews.llvm.org/D125993
Made library registration conditional and skip it in the __kmp_atfork_child
handler, postponed it till middle initialization in the child.
This fixes the problem of applications those use e.g. popen/pclose
which terminate the forked child process.
Differential Revision: https://reviews.llvm.org/D125996
When many nested teams are formed, __kmp_threads may be reallocated
to accommodate new threads. This reallocation causes a data
race when another existing team's thread simultaneously references
__kmp_threads. This patch keeps the old thread arrays around until library
shutdown so these lingering references can complete without issue and
access to __kmp_threads remains a simple array reference.
Fixes: https://github.com/llvm/llvm-project/issues/54708
Differential Revision: https://reviews.llvm.org/D125013
Currently the library ignores requested wait policy in the presence
of tasking. Threads always actively spin. The patch fixes this problem
making the wait policy passive if this explicitly requested by user.
Differential Revision: https://reviews.llvm.org/D123044
The target allocators have been supported for NVPTX offloading for
awhile. The tests should use the allocators instead of calling the
functions manually. Also the comments indicating these being a preview
should be removed.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D123242
Add use of TPAUSE (from WAITPKG) to the runtime for Intel hardware,
with an envirable to turn it on in a particular C-state. Always uses
TPAUSE if it is selected and enabled by Intel hardware and presence of
WAITPKG, and if not, falls back to old way of checking
__kmp_use_yield, etc.
Differential Revision: https://reviews.llvm.org/D115758
This patch implements teams affinity on the host.
The default is spread. A user can specify either spread, close, or
primary using KMP_TEAMS_PROC_BIND environment variable. Unlike
OMP_PROC_BIND, KMP_TEAMS_PROC_BIND is only a single value and is not a
list of values. The values follow the same semantics under the OpenMP
specification for parallel regions except T is the number of teams in
a league instead of the number of threads in a parallel region.
Differential Revision: https://reviews.llvm.org/D109921
Two-level distributed barrier is a new experimental barrier designed
for Intel hardware that has better performance in some cases than the
default hyper barrier.
This barrier is designed to handle fine granularity parallelism where
barriers are used frequently with little compute and memory access
between barriers. There is no need to use it for codes with few
barriers and large granularity compute, or memory intensive
applications, as little difference will be seen between this barrier
and the default hyper barrier. This barrier is designed to work
optimally with a fixed number of threads, and has a significant setup
time, so should NOT be used in situations where the number of threads
in a team is varied frequently.
The two-level distributed barrier is off by default -- hyper barrier
is used by default. To use this barrier, you must set all barrier
patterns to use this type, because it will not work with other barrier
patterns. Thus, to turn it on, the following settings are required:
KMP_FORKJOIN_BARRIER_PATTERN=dist,dist
KMP_PLAIN_BARRIER_PATTERN=dist,dist
KMP_REDUCTION_BARRIER_PATTERN=dist,dist
Branching factors (set with KMP_FORKJOIN_BARRIER, KMP_PLAIN_BARRIER,
and KMP_REDUCTION_BARRIER) are ignored by the two-level distributed
barrier.
Patch fixed for ITTNotify disabled builds and non-x86 builds
Co-authored-by: Jonathan Peyton <jonathan.l.peyton@intel.com>
Co-authored-by: Vladislav Vinogradov <vlad.vinogradov@intel.com>
Differential Revision: https://reviews.llvm.org/D103121
Two-level distributed barrier is a new experimental barrier designed
for Intel hardware that has better performance in some cases than the
default hyper barrier.
This barrier is designed to handle fine granularity parallelism where
barriers are used frequently with little compute and memory access
between barriers. There is no need to use it for codes with few
barriers and large granularity compute, or memory intensive
applications, as little difference will be seen between this barrier
and the default hyper barrier. This barrier is designed to work
optimally with a fixed number of threads, and has a significant setup
time, so should NOT be used in situations where the number of threads
in a team is varied frequently.
The two-level distributed barrier is off by default -- hyper barrier
is used by default. To use this barrier, you must set all barrier
patterns to use this type, because it will not work with other barrier
patterns. Thus, to turn it on, the following settings are required:
KMP_FORKJOIN_BARRIER_PATTERN=dist,dist
KMP_PLAIN_BARRIER_PATTERN=dist,dist
KMP_REDUCTION_BARRIER_PATTERN=dist,dist
Branching factors (set with KMP_FORKJOIN_BARRIER, KMP_PLAIN_BARRIER,
and KMP_REDUCTION_BARRIER) are ignored by the two-level distributed
barrier.
Differential Revision: https://reviews.llvm.org/D103121
Nesting mode is a new experimental feature in the OpenMP
runtime. It allows a user to set up nesting for an application in a
way that corresponds to the hardware topology levels on the machine an
application is being run on. For example, if a machine has 2 sockets,
each with 12 cores, then use of nesting mode could set up an outer
level of nesting that uses 2 threads per parallel region, and an inner
level of nesting that uses 12 threads per parallel region.
Nesting mode is controlled with the KMP_NESTING_MODE environment
variable as follows:
1) KMP_NESTING_MODE = 0: Nesting mode is off (default); max-active-levels-var
is set to 1 (the default -- nesting is off, nested parallel regions
are serialized).
2) KMP_NESTING_MODE = 1: Nesting mode is on, and a number of threads
will be assigned for each level discovered in the machine topology;
max-active-levels-var is set to the number of levels discovered.
3) KMP_NESTING_MODE = n, n>1: [Note: this option is experimental and may change
or be removed in the future.] Nesting mode is on, and a number of
threads will be assigned for each topology level discovered on the
machine, up to k<=n levels (since there may be fewer than n levels
discovered in the topology), and beyond the kth level, nested parallel
regions will be serialized; NOTE: max-active-levels-var is 1 (the default --
nesting is off, and nested parallel regions are serialized until the
user changes max-active-levels-var.
If the user sets OMP_NUM_THREADS or OMP_MAX_ACTIVE_LEVELS, they will
override KMP_NESTING_MODE settings for the associated environment
variables. The detected topology may be limited by an affinity mask
setting on the initial thread, or if the user sets KMP_HW_SUBSET. See
also: KMP_HOT_TEAMS_MAX_LEVEL for controlling use of hot teams for
nested parallel regions. Note that this feature only sets numbers of
threads used at nesting levels. The user should make use of
OMP_PLACES and OMP_PROC_BIND or KMP_AFFINITY for affinitizing those
threads, if desired.
Differential Revision: https://reviews.llvm.org/D102188
This patch does the following:
1) Introduce kmp_topology_t as the runtime-friendly structure (the
corresponding global variable is __kmp_topology) to determine the
exact machine topology which can vary widely among current and future
architectures. The current design is not easy to expand beyond the assumed
three layer topology: sockets, cores, and threads so a rework capable of
using the existing KMP_AFFINITY mechanisms is required.
This new topology structure has:
* The depth and types of the topology
* Ratio count for each consecutive level (e.g., number of cores per
socket, number of threads per core)
* Absolute count for each level (e.g., 2 sockets, 16 cores, 32 threads)
* Equivalent topology layer map (e.g., Numa domain is equivalent to
socket, L1/L2 cache equivalent to core)
* Whether it is uniform or not
The hardware threads are represented with the kmp_hw_thread_t
structure. This structure contains the ids (e.g., socket 0, core 1,
thread 0) and other information grabbed from the previous Address
structure. The kmp_topology_t structure contains an array of these.
2) Generalize the KMP_HW_SUBSET envirable for the new
kmp_topology_t structure. The algorithm doesn't assume any order with
tiles,numa domains,sockets,cores,threads. Instead it just parses the
envirable, makes sure it is consistent with the detected topology
(including taking into account equivalent layers) and then trims away
the unneeded subset of hardware threads. To enable this, a new
kmp_hw_subset_t structure is introduced which contains a vector of
items (hardware type, number user wants, offset). Any keyword within
__kmp_hw_get_keyword() can be used as a name and can be shortened as
well. e.g.,
KMP_HW_SUBSET=1s,2numa,4tile,2c,3t can be used on the KNL SNC-4 machine.
3) Simplify topology detection functions so they only do the singular
task of detecting the machine's topology. Printing, and all
canonicalizing functionality is now done afterwards. So many lines of
duplicated code are eliminated.
4) Add new ll_caches and numa_domains to OMP_PLACES, and
consequently, KMP_AFFINITY's granularity setting. All the names within
__kmp_hw_get_keyword() are available for use in OMP_PLACES or
KMP_AFFINITY's granularity setting.
5) Simplify and future-proof code where explicit lists of allowed
affinity settings keywords inside if() conditions.
6) Add x86 CPUID leaf 4 cache detection to existing x2apic id method
so equivalent caches could be detected (in particular for the ll_caches
place).
Differential Revision: https://reviews.llvm.org/D100997
and __kmpc_end_masked. The "master" construct is deprecated. Changed
proc-bind keyword from "master" to "primary". Use of both master
construct and master as proc-bind keyword is still allowed, but
deprecated.
Remove references to "master" in comments and strings, and replace
with "primary" or "primary thread". Function names and variables were
not touched, nor were references to deprecated master construct. These
can be updated over time. No new code should refer to master.
This is a preview of allocator support for target memory that depends on the
offload runtime API which allocates memory as described below.
llvm_omp_target_alloc_host(size_t size, int device_num);
-- Returns non-migratable memory owned by host.
-- Memory is accessible by host and device(s).
llvm_omp_target_alloc_shared(size_t size, int device_num);
-- Returns migratable memory owned by host and device.
-- Memory is accessible by host and device.
llvm_omp_target_alloc_device(size_t size, int device_num);
-- Returns memory owned by device.
-- Memory is only accessible by device.
New memory space and predefined allocator names are
-- llvm_omp_target_host_mem_space
-- llvm_omp_target_shared_mem_space
-- llvm_omp_target_device_mem_space
-- llvm_omp_target_host_mem_alloc
-- llvm_omp_target_shared_mem_alloc
-- llvm_omp_target_device_mem_alloc
Differential Revision: https://reviews.llvm.org/D96669
This patch introduces a new environment variable to force monotonic
behavior for users that absolutely need it. This is in anticipation
of 5.0 change that uses non-monotonic behavior for dynamic scheduling
by default. Fixes for that and the actual switch are coming soon.
Differential Revision: https://reviews.llvm.org/D95263
This patch adds the new algorithm for topology discovery using cpuid
leaf 1f. Only the new die level is detected and integrated into the
current affinity mechanisms including KMP_AFFINITY (granularity level
and compact/scatter algorithm), OMP_PLACES=dies, and KMP_HW_SUBSET.
Differential Revision: https://reviews.llvm.org/D95157
The basic design is to create an outer-most parallel team. It is not a regular team because it is only created when the first hidden helper task is encountered, and is only responsible for the execution of hidden helper tasks. We first use `pthread_create` to create a new thread, let's call it the initial and also the main thread of the hidden helper team. This initial thread then initializes a new root, just like what RTL does in initialization. After that, it directly calls `__kmpc_fork_call`. It is like the initial thread encounters a parallel region. The wrapped function for this team is, for main thread, which is the initial thread that we create via `pthread_create` on Linux, waits on a condition variable. The condition variable can only be signaled when RTL is being destroyed. For other work threads, they just do nothing. The reason that main thread needs to wait there is, in current implementation, once the main thread finishes the wrapped function of this team, it starts to free the team which is not what we want.
Two environment variables, `LIBOMP_NUM_HIDDEN_HELPER_THREADS` and `LIBOMP_USE_HIDDEN_HELPER_TASK`, are also set to configure the number of threads and enable/disable this feature. By default, the number of hidden helper threads is 8.
Here are some open issues to be discussed:
1. The main thread goes to sleeping when the initialization is finished. As Andrey mentioned, we might need it to be awaken from time to time to do some stuffs. What kind of update/check should be put here?
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D77609
The basic design is to create an outer-most parallel team. It is not a regular team because it is only created when the first hidden helper task is encountered, and is only responsible for the execution of hidden helper tasks. We first use `pthread_create` to create a new thread, let's call it the initial and also the main thread of the hidden helper team. This initial thread then initializes a new root, just like what RTL does in initialization. After that, it directly calls `__kmpc_fork_call`. It is like the initial thread encounters a parallel region. The wrapped function for this team is, for main thread, which is the initial thread that we create via `pthread_create` on Linux, waits on a condition variable. The condition variable can only be signaled when RTL is being destroyed. For other work threads, they just do nothing. The reason that main thread needs to wait there is, in current implementation, once the main thread finishes the wrapped function of this team, it starts to free the team which is not what we want.
Two environment variables, `LIBOMP_NUM_HIDDEN_HELPER_THREADS` and `LIBOMP_USE_HIDDEN_HELPER_TASK`, are also set to configure the number of threads and enable/disable this feature. By default, the number of hidden helper threads is 8.
Here are some open issues to be discussed:
1. The main thread goes to sleeping when the initialization is finished. As Andrey mentioned, we might need it to be awaken from time to time to do some stuffs. What kind of update/check should be put here?
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D77609
These changes add support for Intel's umonitor/umwait usage in wait
code, for architectures that support those intrinsic functions. Usage of
umonitor/umwait is off by default, but can be turned on by setting the
KMP_USER_LEVEL_MWAIT environment variable.
Differential Revision: https://reviews.llvm.org/D91189
There's no need to initialize variables with static storage duration
because they're implicitly initialized to zero. See
https://en.cppreference.com/w/c/language/initialization#Implicit_initialization
I think that's already relied upon because the supplied 0 only sets
'kmp_time_global_t g_time;' in 'struct kmp_base_global'. The other fields
are not set in the code, but implicitly initialized by the compiler.
Differential Revision: https://reviews.llvm.org/D66292
llvm-svn: 370943
Remove all older OMP spec versioning from the runtime and build system.
Patch by Terry Wilmarth
Differential Revision: https://reviews.llvm.org/D64534
llvm-svn: 365963
* Replace HBWMALLOC API with more general MEMKIND API, new functions
and variables added.
* Have libmemkind.so loaded when accessible.
* Redirect memspaces to default one except for high bandwidth which
is processed separately.
* Ignore some allocator traits e.g., sync_hint, access, pinned, while
others are processed normally e.g., alignment, pool_size, fallback,
fb_data, partition.
* Add tests for memory management
Patch by Andrey Churbanov
Differential Revision: https://reviews.llvm.org/D59783
llvm-svn: 357929
This patch cleans up the bookkeeping code for the load balancing dynamic mode.
When a thread is moved to or from the thread pool, the th_active_in_pool flag
and the __kmp_thread_pool_active_nth global counter are both updated. This
removes the need for the corrective code in the main wait loop. Another global
counter, __kmp_thread_pool_nth, was removed completely, as it was only used for
debugging, but was not under KMP_DEBUG.
Patch by Terry Wilmarth
Differential Revision: https://reviews.llvm.org/D59508
llvm-svn: 357927
Nest-var, OMP_NESTED, omp_set_nested()., and omp_get_nested() have been
deprecated in the 5.0 spec. Initial nesting info is now derived from
OMP_MAX_ACTIVE_LEVELS, OMP_NUM_THREADS, and OMP_PROC_BIND.
This patch deprecates the internal ICV that corresponds to nest-var, and
replaces it with the max-active-levels-var ICV to determine nesting. The
change still allows for use of OMP_NESTED (according to 5.0 changes),
omp_get_nested, and omp_set_nested, which have had deprecation messages
added to them. The change allows certain settings of OMP_NUM_THREADS,
OMP_PROC_BIND, and OMP_MAX_ACTIVE_LEVELS to turn on nesting, but
OMP_NESTED=0 will still force nesting to be off.
The runtime now prints informative messages about deprecation of
OMP_NESTED, omp_set_nested(), and omp_get_nested(), when those
environment variables or routines are used. It also prints deprecated
message in output for KMP_SETTINGS and OMP_DISPLAY_ENV for OMP_NESTED.
This patch also fixes OMP_DISPLAY_ENV output for OMP_TARGET_OFFLOAD.
Patch by Terry Wilmarth
Differential Revision: https://reviews.llvm.org/D58408
llvm-svn: 355138
This patch cleans up the yielding code and makes it optional. An
environment variable, KMP_USE_YIELD, was added. Yielding is still
on by default (KMP_USE_YIELD=1), but can be turned off completely
(KMP_USE_YIELD=0), or turned on only when oversubscription is detected
(KMP_USE_YIELD=2). Note that oversubscription cannot always be detected
by the runtime (for example, when the runtime is initialized and the
process forks, oversubscription cannot be detected currently over
multiple instances of the runtime).
Because yielding can be controlled by user now, the library mode
settings (from KMP_LIBRARY) for throughput and turnaround have been
adjusted by altering blocktime, unless that was also explicitly set.
In the original code, there were a number of places where a double yield
might have been done under oversubscription. This version checks
oversubscription and if that's not going to yield, then it does
the spin check.
Patch by Terry Wilmarth
Differential Revision: https://reviews.llvm.org/D58148
llvm-svn: 355120
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351648
Add omp_pause_resource and omp_pause_resource_all API and enum, plus stub for
internal implementation. Implemented callable helper function to do local pause,
and added basic functionality for hard and soft pause.
Patch by Terry Wilmarth
Differential Revision: https://reviews.llvm.org/D55078
llvm-svn: 351372
Summary:
Two things:
1. Those two variables had the wrong sigdness, which was resulting in "sign mismatch in comparison" warning.
2. The whole `kmp_debugger.cpp` wasn't being built, or rather, it was being built as-if `USE_DEBUGGER` was off,
thus, nothing provided the definition of `__kmp_omp_debug_struct_info`, `__kmp_debugging`.
Makes sense, because `USE_DEBUGGER` is set in `kmp_config.h`, which is not included explicitly.
It is included by `kmp.h`, but that one is only included inside of the `#if USE_DEBUGGER` block..
I *think* this is the only source file with this issue,
everything else seem to `#include` either `kmp.h` or `kmp_config.h`.
The alternative solution would be to add `add_compile_options(-include kmp_config.h)` in CMake.
I did verify that `__kmp_omp_debug_struct_info` becomes available with this patch.
Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=38612 | PR38612 ]].
Reviewers: AndreyChurbanov, jlpeyton, Hahnfeld
Reviewed By: jlpeyton
Subscribers: guansong, jfb, openmp-commits
Tags: #openmp
Differential Revision: https://reviews.llvm.org/D55783
llvm-svn: 351019
This patch adds the affinity format functionality introduced in OpenMP 5.0.
This patch adds: Two new environment variables:
OMP_DISPLAY_AFFINITY=TRUE|FALSE
OMP_AFFINITY_FORMAT=<string>
and Four new API:
1) omp_set_affinity_format()
2) omp_get_affinity_format()
3) omp_display_affinity()
4) omp_capture_affinity()
The affinity format functionality has two ICV's associated with it:
affinity-display-var (bool) and affinity-format-var (string).
The affinity-display-var enables/disables the functionality through the
envirable OMP_DISPLAY_AFFINITY. The affinity-format-var is a formatted
string with the special field types beginning with a '%' character
similar to printf
For example, the affinity-format-var could be:
"OMP: host:%H pid:%P OStid:%i num_threads:%N thread_num:%n affinity:{%A}"
The affinity-format-var is displayed by every thread implicitly at the beginning
of a parallel region when any thread's affinity has changed (including a brand
new thread being spawned), or explicitly using the omp_display_affinity() API.
The omp_capture_affinity() function can capture the affinity-format-var in a
char buffer. And omp_set|get_affinity_format() allow the user to set|get the
affinity-format-var explicitly at runtime. omp_capture_affinity() and
omp_get_affinity_format() both return the number of characters needed to hold
the entire string it tried to make (not including NULL character). If not
enough buffer space is available,
both these functions truncate their output.
Differential Revision: https://reviews.llvm.org/D55148
llvm-svn: 349089
Implemented omp_alloc, omp_free, omp_{set,get}_default_allocator entries,
and OMP_ALLOCATOR environment variable.
Added support for HBW memory on Linux if libmemkind.so library is accessible
(dynamic library only, no support for static libraries).
Only used stable API (hbwmalloc) of the memkind library
though we may consider using experimental API in future.
The ICV def-allocator-var is implemented per implicit task similar to
place-partition-var. In the absence of a requested allocator, the uses the
default allocator.
Predefined allocators (the only ones currently available) are made similar
for C and Fortran, - pointers (long integers) with values 1 to 8.
Patch by Andrey Churbanov
Differential Revision: https://reviews.llvm.org/D51232
llvm-svn: 341687
This change fixes build errors when building a runtime with adaptive lock stats
enabled. Most of the errors were due to the recent changes in the runtime, but
it seems that we have not tried to build this debug runtime on Windows for a
long time.
Patch by Hansang Bae
Differential Revision: https://reviews.llvm.org/D49823
llvm-svn: 338277
This patch introduces the logic implementing hierarchical scheduling.
First and foremost, hierarchical scheduling is off by default
To enable, use -DLIBOMP_USE_HIER_SCHED=On during CMake's configure stage.
This work is based off if the IWOMP paper:
"Workstealing and Nested Parallelism in SMP Systems"
Hierarchical scheduling is the layering of OpenMP schedules for different layers
of the memory hierarchy. One can have multiple layers between the threads and
the global iterations space. The threads will go up the hierarchy to grab
iterations, using possibly a different schedule & chunk for each layer.
[ Global iteration space (0-999) ]
(use static)
[ L1 | L1 | L1 | L1 ]
(use dynamic,1)
[ T0 T1 | T2 T3 | T4 T5 | T6 T7 ]
In the example shown above, there are 8 threads and 4 L1 caches begin targeted.
If the topology indicates that there are two threads per core, then two
consecutive threads will share the data of one L1 cache unit. This example
would have the iteration space (0-999) split statically across the four L1
caches (so the first L1 would get (0-249), the second would get (250-499), etc).
Then the threads will use a dynamic,1 schedule to grab iterations from the L1
cache units. There are currently four supported layers: L1, L2, L3, NUMA
OMP_SCHEDULE can now read a hierarchical schedule with this syntax:
OMP_SCHEDULE='EXPERIMENTAL LAYER,SCHED[,CHUNK][:LAYER,SCHED[,CHUNK]...]:SCHED,CHUNK
And OMP_SCHEDULE can still read the normal SCHED,CHUNK syntax from before
I've kept most of the hierarchical scheduling logic inside kmp_dispatch_hier.h
to try to keep it separate from the rest of the code.
Differential Revision: https://reviews.llvm.org/D47962
llvm-svn: 336571
These are preliminary changes that attempt to use C++11 Atomics in the runtime.
We are expecting better portability with this change across architectures/OSes.
Here is the summary of the changes.
Most variables that need synchronization operation were converted to generic
atomic variables (std::atomic<T>). Variables that are updated with combined CAS
are packed into a single atomic variable, and partial read/write is done
through unpacking/packing
Patch by Hansang Bae
Differential Revision: https://reviews.llvm.org/D47903
llvm-svn: 336563
Added settings code to read OMP_TARGET_OFFLOAD environment variable. Added
target-offload-var ICV as __kmp_target_offload, set via OMP_TARGET_OFFLOAD,
if available, otherwise defaulting to DEFAULT. Valid values for the ICV are
specified as enum values {0,1,2} for disabled, default, and mandatory. An
internal API access function __kmpc_get_target_offload is provided.
Patch by Terry Wilmarth
Differential Revision: https://reviews.llvm.org/D44577
llvm-svn: 328046
All architectures except x86_64 used the linear barrier implementation
by default which doesn't give good performance for a larger number
of threads.
Improvements for PARALLEL overhead (EPCC) with this patch on a Power8
system (2 sockets x 10 cores x 8 threads, OMP_PLACES=cores)
20 threads: 4.55us -> 3.49us
40 threads: 8.84us -> 4.06us
80 threads: 19.18us -> 4.74us
160 threads: 54.22us -> 6.73us
Differential Revision: https://reviews.llvm.org/D40358
llvm-svn: 320152
