Blame view
tools/cub-1.8.0/cub/warp/specializations/warp_reduce_smem.cuh
13.9 KB
8dcb6dfcb
first commit
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 |
/******************************************************************************
* Copyright (c) 2011, Duane Merrill. All rights reserved.
* Copyright (c) 2011-2018, NVIDIA CORPORATION. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the NVIDIA CORPORATION nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************/
/**
* \file
* cub::WarpReduceSmem provides smem-based variants of parallel reduction of items partitioned across a CUDA thread warp.
*/
#pragma once
#include "../../thread/thread_operators.cuh"
#include "../../thread/thread_load.cuh"
#include "../../thread/thread_store.cuh"
#include "../../util_type.cuh"
#include "../../util_namespace.cuh"
/// Optional outer namespace(s)
CUB_NS_PREFIX
/// CUB namespace
namespace cub {
/**
* \brief WarpReduceSmem provides smem-based variants of parallel reduction of items partitioned across a CUDA thread warp.
*/
template <
typename T, ///< Data type being reduced
int LOGICAL_WARP_THREADS, ///< Number of threads per logical warp
int PTX_ARCH> ///< The PTX compute capability for which to to specialize this collective
struct WarpReduceSmem
{
/******************************************************************************
* Constants and type definitions
******************************************************************************/
enum
{
/// Whether the logical warp size and the PTX warp size coincide
IS_ARCH_WARP = (LOGICAL_WARP_THREADS == CUB_WARP_THREADS(PTX_ARCH)),
/// Whether the logical warp size is a power-of-two
IS_POW_OF_TWO = PowerOfTwo<LOGICAL_WARP_THREADS>::VALUE,
/// The number of warp scan steps
STEPS = Log2<LOGICAL_WARP_THREADS>::VALUE,
/// The number of threads in half a warp
HALF_WARP_THREADS = 1 << (STEPS - 1),
/// The number of shared memory elements per warp
WARP_SMEM_ELEMENTS = LOGICAL_WARP_THREADS + HALF_WARP_THREADS,
/// FlagT status (when not using ballot)
UNSET = 0x0, // Is initially unset
SET = 0x1, // Is initially set
SEEN = 0x2, // Has seen another head flag from a successor peer
};
/// Shared memory flag type
typedef unsigned char SmemFlag;
/// Shared memory storage layout type (1.5 warps-worth of elements for each warp)
struct _TempStorage
{
T reduce[WARP_SMEM_ELEMENTS];
SmemFlag flags[WARP_SMEM_ELEMENTS];
};
// Alias wrapper allowing storage to be unioned
struct TempStorage : Uninitialized<_TempStorage> {};
/******************************************************************************
* Thread fields
******************************************************************************/
_TempStorage &temp_storage;
unsigned int lane_id;
unsigned int member_mask;
/******************************************************************************
* Construction
******************************************************************************/
/// Constructor
__device__ __forceinline__ WarpReduceSmem(
TempStorage &temp_storage)
:
temp_storage(temp_storage.Alias()),
lane_id(IS_ARCH_WARP ?
LaneId() :
LaneId() % LOGICAL_WARP_THREADS),
member_mask((0xffffffff >> (32 - LOGICAL_WARP_THREADS)) << ((IS_ARCH_WARP || !IS_POW_OF_TWO ) ?
0 : // arch-width and non-power-of-two subwarps cannot be tiled with the arch-warp
((LaneId() / LOGICAL_WARP_THREADS) * LOGICAL_WARP_THREADS)))
{}
/******************************************************************************
* Utility methods
******************************************************************************/
//---------------------------------------------------------------------
// Regular reduction
//---------------------------------------------------------------------
/**
* Reduction step
*/
template <
bool ALL_LANES_VALID, ///< Whether all lanes in each warp are contributing a valid fold of items
typename ReductionOp,
int STEP>
__device__ __forceinline__ T ReduceStep(
T input, ///< [in] Calling thread's input
int valid_items, ///< [in] Total number of valid items across the logical warp
ReductionOp reduction_op, ///< [in] Reduction operator
Int2Type<STEP> /*step*/)
{
const int OFFSET = 1 << STEP;
// Share input through buffer
ThreadStore<STORE_VOLATILE>(&temp_storage.reduce[lane_id], input);
WARP_SYNC(member_mask);
// Update input if peer_addend is in range
if ((ALL_LANES_VALID && IS_POW_OF_TWO) || ((lane_id + OFFSET) < valid_items))
{
T peer_addend = ThreadLoad<LOAD_VOLATILE>(&temp_storage.reduce[lane_id + OFFSET]);
input = reduction_op(input, peer_addend);
}
WARP_SYNC(member_mask);
return ReduceStep<ALL_LANES_VALID>(input, valid_items, reduction_op, Int2Type<STEP + 1>());
}
/**
* Reduction step (terminate)
*/
template <
bool ALL_LANES_VALID, ///< Whether all lanes in each warp are contributing a valid fold of items
typename ReductionOp>
__device__ __forceinline__ T ReduceStep(
T input, ///< [in] Calling thread's input
int valid_items, ///< [in] Total number of valid items across the logical warp
ReductionOp /*reduction_op*/, ///< [in] Reduction operator
Int2Type<STEPS> /*step*/)
{
return input;
}
//---------------------------------------------------------------------
// Segmented reduction
//---------------------------------------------------------------------
/**
* Ballot-based segmented reduce
*/
template <
bool HEAD_SEGMENTED, ///< Whether flags indicate a segment-head or a segment-tail
typename FlagT,
typename ReductionOp>
__device__ __forceinline__ T SegmentedReduce(
T input, ///< [in] Calling thread's input
FlagT flag, ///< [in] Whether or not the current lane is a segment head/tail
ReductionOp reduction_op, ///< [in] Reduction operator
Int2Type<true> /*has_ballot*/) ///< [in] Marker type for whether the target arch has ballot functionality
{
// Get the start flags for each thread in the warp.
int warp_flags = WARP_BALLOT(flag, member_mask);
if (!HEAD_SEGMENTED)
warp_flags <<= 1;
// Keep bits above the current thread.
warp_flags &= LaneMaskGt();
// Accommodate packing of multiple logical warps in a single physical warp
if (!IS_ARCH_WARP)
{
warp_flags >>= (LaneId() / LOGICAL_WARP_THREADS) * LOGICAL_WARP_THREADS;
}
// Find next flag
int next_flag = __clz(__brev(warp_flags));
// Clip the next segment at the warp boundary if necessary
if (LOGICAL_WARP_THREADS != 32)
next_flag = CUB_MIN(next_flag, LOGICAL_WARP_THREADS);
#pragma unroll
for (int STEP = 0; STEP < STEPS; STEP++)
{
const int OFFSET = 1 << STEP;
// Share input into buffer
ThreadStore<STORE_VOLATILE>(&temp_storage.reduce[lane_id], input);
WARP_SYNC(member_mask);
// Update input if peer_addend is in range
if (OFFSET + lane_id < next_flag)
{
T peer_addend = ThreadLoad<LOAD_VOLATILE>(&temp_storage.reduce[lane_id + OFFSET]);
input = reduction_op(input, peer_addend);
}
WARP_SYNC(member_mask);
}
return input;
}
/**
* Smem-based segmented reduce
*/
template <
bool HEAD_SEGMENTED, ///< Whether flags indicate a segment-head or a segment-tail
typename FlagT,
typename ReductionOp>
__device__ __forceinline__ T SegmentedReduce(
T input, ///< [in] Calling thread's input
FlagT flag, ///< [in] Whether or not the current lane is a segment head/tail
ReductionOp reduction_op, ///< [in] Reduction operator
Int2Type<false> /*has_ballot*/) ///< [in] Marker type for whether the target arch has ballot functionality
{
enum
{
UNSET = 0x0, // Is initially unset
SET = 0x1, // Is initially set
SEEN = 0x2, // Has seen another head flag from a successor peer
};
// Alias flags onto shared data storage
volatile SmemFlag *flag_storage = temp_storage.flags;
SmemFlag flag_status = (flag) ? SET : UNSET;
for (int STEP = 0; STEP < STEPS; STEP++)
{
const int OFFSET = 1 << STEP;
// Share input through buffer
ThreadStore<STORE_VOLATILE>(&temp_storage.reduce[lane_id], input);
WARP_SYNC(member_mask);
// Get peer from buffer
T peer_addend = ThreadLoad<LOAD_VOLATILE>(&temp_storage.reduce[lane_id + OFFSET]);
WARP_SYNC(member_mask);
// Share flag through buffer
flag_storage[lane_id] = flag_status;
// Get peer flag from buffer
SmemFlag peer_flag_status = flag_storage[lane_id + OFFSET];
// Update input if peer was in range
if (lane_id < LOGICAL_WARP_THREADS - OFFSET)
{
if (HEAD_SEGMENTED)
{
// Head-segmented
if ((flag_status & SEEN) == 0)
{
// Has not seen a more distant head flag
if (peer_flag_status & SET)
{
// Has now seen a head flag
flag_status |= SEEN;
}
else
{
// Peer is not a head flag: grab its count
input = reduction_op(input, peer_addend);
}
// Update seen status to include that of peer
flag_status |= (peer_flag_status & SEEN);
}
}
else
{
// Tail-segmented. Simply propagate flag status
if (!flag_status)
{
input = reduction_op(input, peer_addend);
flag_status |= peer_flag_status;
}
}
}
}
return input;
}
/******************************************************************************
* Interface
******************************************************************************/
/**
* Reduction
*/
template <
bool ALL_LANES_VALID, ///< Whether all lanes in each warp are contributing a valid fold of items
typename ReductionOp>
__device__ __forceinline__ T Reduce(
T input, ///< [in] Calling thread's input
int valid_items, ///< [in] Total number of valid items across the logical warp
ReductionOp reduction_op) ///< [in] Reduction operator
{
return ReduceStep<ALL_LANES_VALID>(input, valid_items, reduction_op, Int2Type<0>());
}
/**
* Segmented reduction
*/
template <
bool HEAD_SEGMENTED, ///< Whether flags indicate a segment-head or a segment-tail
typename FlagT,
typename ReductionOp>
__device__ __forceinline__ T SegmentedReduce(
T input, ///< [in] Calling thread's input
FlagT flag, ///< [in] Whether or not the current lane is a segment head/tail
ReductionOp reduction_op) ///< [in] Reduction operator
{
return SegmentedReduce<HEAD_SEGMENTED>(input, flag, reduction_op, Int2Type<(PTX_ARCH >= 200)>());
}
};
} // CUB namespace
CUB_NS_POSTFIX // Optional outer namespace(s)
|