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Details: - Defined a new struct datatype, rntm_t (runtime), to house the thrloop field of the cntx_t (context). The thrloop array holds the number of ways of parallelism (thread "splits") to extract per level-3 algorithmic loop until those values can be used to create a corresponding node in the thread control tree (thrinfo_t structure), which (for any given level-3 invocation) usually happens by the time the macrokernel is called for the first time. - Relocating the thrloop from the cntx_t remedies a thread-safety issue when invoking level-3 operations from two or more application threads. The race condition existed because the cntx_t, a pointer to which is usually queried from the global kernel structure (gks), is supposed to be a read-only. However, the previous code would write to the cntx_t's thrloop field *after* it had been queried, thus violating its read-only status. In practice, this would not cause a problem when a sequential application made a multithreaded call to BLIS, nor when two or more application threads used the same parallelization scheme when calling BLIS, because in either case all application theads would be using the same ways of parallelism for each loop. The true effects of the race condition were limited to situations where two or more application theads used *different* parallelization schemes for any given level-3 call. - In remedying the above race condition, the application or calling library can now specify the parallelization scheme on a per-call basis. All that is required is that the thread encode its request for parallelism into the rntm_t struct prior to passing the address of the rntm_t to one of the expert interfaces of either the typed or object APIs. This allows, for example, one application thread to extract 4-way parallelism from a call to gemm while another application thread requests 2-way parallelism. Or, two threads could each request 4-way parallelism, but from different loops. - A rntm_t* parameter has been added to the function signatures of most of the level-3 implementation stack (with the most notable exception being packm) as well as all level-1v, -1d, -1f, -1m, and -2 expert APIs. (A few internal functions gained the rntm_t* parameter even though they currently have no use for it, such as bli_l3_packm().) This required some internal calls to some of those functions to be updated since BLIS was already using those operations internally via the expert interfaces. For situations where a rntm_t object is not available, such as within packm/unpackm implementations, NULL is passed in to the relevant expert interfaces. This is acceptable for now since parallelism is not obtained for non-level-3 operations. - Revamped how global parallelism is encoded. First, the conventional environment variables such as BLIS_NUM_THREADS and BLIS_*_NT are only read once, at library initialization. (Thanks to Nathaniel Smith for suggesting this to avoid repeated calls getenv(), which can be slow.) Those values are recorded to a global rntm_t object. Public APIs, in bli_thread.c, are still available to get/set these values from the global rntm_t, though now the "set" functions have additional logic to ensure that the values are set in a synchronous manner via a mutex. If/when NULL is passed into an expert API (meaning the user opted to not provide a custom rntm_t), the values from the global rntm_t are copied to a local rntm_t, which is then passed down the function stack. Calling a basic API is equivalent to calling the expert APIs with NULL for the cntx and rntm parameters, which means the semantic behavior of these basic APIs (vis-a-vis multithreading) is unchanged from before. - Renamed bli_cntx_set_thrloop_from_env() to bli_rntm_set_ways_for_op() and reimplemented, with the function now being able to treat the incoming rntm_t in a manner agnostic to its origin--whether it came from the application or is an internal copy of the global rntm_t. - Removed various global runtime APIs for setting the number of ways of parallelism for individual loops (e.g. bli_thread_set_*_nt()) as well as the corresponding "get" functions. The new model simplifies these interfaces so that one must either set the total number of threads, OR set all of the ways of parallelism for each loop simultaneously (in a single function call). - Updated sandbox/ref99 according to above changes. - Rewrote/augmented docs/Multithreading.md to document the three methods (and two specific ways within each method) of requesting parallelism in BLIS. - Removed old, disabled code from bli_l3_thrinfo.c. - Whitespace changes to code (e.g. bli_obj.c) and docs/BuildSystem.md.
220 lines
6.0 KiB
C
220 lines
6.0 KiB
C
/*
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BLIS
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An object-based framework for developing high-performance BLAS-like
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libraries.
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Copyright (C) 2014, The University of Texas at Austin
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Copyright (C) 2016, Hewlett Packard Enterprise Development LP
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of The University of Texas at Austin nor the names
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of its contributors may be used to endorse or promote products
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derived from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef BLIS_THREAD_H
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#define BLIS_THREAD_H
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// Include thread communicator (thrcomm_t) object definitions and prototypes.
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#include "bli_thrcomm.h"
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// Include thread info (thrinfo_t) object definitions and prototypes.
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#include "bli_thrinfo.h"
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// Include some operation-specific thrinfo_t prototypes.
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// Note that the bli_packm_thrinfo.h must be included before the others!
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#include "bli_packm_thrinfo.h"
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#include "bli_l3_thrinfo.h"
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// Initialization-related prototypes.
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void bli_thread_init( void );
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void bli_thread_finalize( void );
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#ifdef _MSC_VER
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#define strerror_r(errno,buf,len) strerror_s(buf,len,errno)
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#endif
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// Thread range-related prototypes.
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void bli_thread_get_range_sub
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(
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thrinfo_t* thread,
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dim_t n,
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dim_t bf,
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bool_t handle_edge_low,
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dim_t* start,
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dim_t* end
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);
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#undef GENPROT
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#define GENPROT( opname ) \
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\
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siz_t PASTEMAC0( opname ) \
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( \
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dir_t direct, \
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thrinfo_t* thr, \
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obj_t* a, \
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obj_t* b, \
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obj_t* c, \
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cntl_t* cntl, \
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cntx_t* cntx, \
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dim_t* start, \
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dim_t* end \
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);
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GENPROT( thread_get_range_mdim )
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GENPROT( thread_get_range_ndim )
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#undef GENPROT
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#define GENPROT( opname ) \
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\
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siz_t PASTEMAC0( opname ) \
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( \
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thrinfo_t* thr, \
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obj_t* a, \
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blksz_t* bmult, \
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dim_t* start, \
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dim_t* end \
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);
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GENPROT( thread_get_range_l2r )
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GENPROT( thread_get_range_r2l )
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GENPROT( thread_get_range_t2b )
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GENPROT( thread_get_range_b2t )
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GENPROT( thread_get_range_weighted_l2r )
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GENPROT( thread_get_range_weighted_r2l )
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GENPROT( thread_get_range_weighted_t2b )
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GENPROT( thread_get_range_weighted_b2t )
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dim_t bli_thread_get_range_width_l
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(
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doff_t diagoff_j,
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dim_t m,
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dim_t n_j,
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dim_t j,
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dim_t n_way,
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dim_t bf,
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dim_t bf_left,
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double area_per_thr,
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bool_t handle_edge_low
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);
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siz_t bli_find_area_trap_l
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(
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dim_t m,
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dim_t n,
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doff_t diagoff
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);
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siz_t bli_thread_get_range_weighted_sub
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(
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thrinfo_t* thread,
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doff_t diagoff,
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uplo_t uplo,
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dim_t m,
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dim_t n,
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dim_t bf,
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bool_t handle_edge_low,
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dim_t* j_start_thr,
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dim_t* j_end_thr
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);
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// Level-3 internal function type
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typedef void (*l3int_t)
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(
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obj_t* alpha,
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obj_t* a,
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obj_t* b,
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obj_t* beta,
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obj_t* c,
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cntx_t* cntx,
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rntm_t* rntm,
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cntl_t* cntl,
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thrinfo_t* thread
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);
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// Level-3 thread decorator prototype
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void bli_l3_thread_decorator
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(
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l3int_t func,
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opid_t family,
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obj_t* alpha,
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obj_t* a,
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obj_t* b,
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obj_t* beta,
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obj_t* c,
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cntx_t* cntx,
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rntm_t* rntm,
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cntl_t* cntl
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);
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// -----------------------------------------------------------------------------
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// Factorization and partitioning prototypes
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typedef struct
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{
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dim_t n;
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dim_t sqrt_n;
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dim_t f;
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} bli_prime_factors_t;
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void bli_prime_factorization(dim_t n, bli_prime_factors_t* factors);
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dim_t bli_next_prime_factor(bli_prime_factors_t* factors);
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void bli_partition_2x2(dim_t nthread, dim_t work1, dim_t work2, dim_t* nt1, dim_t* nt2);
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// -----------------------------------------------------------------------------
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dim_t bli_gcd( dim_t x, dim_t y );
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dim_t bli_lcm( dim_t x, dim_t y );
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dim_t bli_ipow( dim_t base, dim_t power );
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// -----------------------------------------------------------------------------
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dim_t bli_thread_get_env( const char* env, dim_t fallback );
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//void bli_thread_set_env( const char* env, dim_t value );
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dim_t bli_thread_get_jc_nt( void );
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dim_t bli_thread_get_pc_nt( void );
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dim_t bli_thread_get_ic_nt( void );
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dim_t bli_thread_get_jr_nt( void );
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dim_t bli_thread_get_ir_nt( void );
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dim_t bli_thread_get_num_threads( void );
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void bli_thread_set_jc_nt( dim_t value );
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void bli_thread_set_pc_nt( dim_t value );
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void bli_thread_set_ic_nt( dim_t value );
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void bli_thread_set_jr_nt( dim_t value );
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void bli_thread_set_ir_nt( dim_t value );
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void bli_thread_set_num_threads( dim_t value );
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void bli_thread_init_rntm( rntm_t* rntm );
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void bli_thread_init_rntm_from_env( rntm_t* rntm );
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#endif
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