elem_block_tune.h

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#ifndef __MATH_ELEM_BLOCK_TUNE_H__
#define __MATH_ELEM_BLOCK_TUNE_H__
/*
 Copyright (c) 2026, The Neko Authors
 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 authors 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 THE
 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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 POSSIBILITY OF SUCH DAMAGE.
*/
 
#include <stdlib.h>
 
/* Sweep the elements per block candidates?
   Measured a 1.6x win on GH200 and
   a loss on MI250X/MI300A, hence the per backend default
 
   Note NEKO_TUNE_ROUNDS and NEKO_TUNE_ITERS below are not specific to
   this sweep: they control the sampling of every candidate the tuner
   times, chunk sizes included. */
#ifndef NEKO_EB_SWEEP_DEFAULT
#define NEKO_EB_SWEEP_DEFAULT 1
#endif
 
#define NEKO_TUNE_INIT 1.0e30f
#define NEKO_TUNE_WARMUP 20
 
static int neko_eb_sweep()
{
  const char *v = getenv("NEKO_EB_TUNE");
 
  if (v != NULL) {
    return (atoi(v) != 0);
  }
  return NEKO_EB_SWEEP_DEFAULT;
}
 
/* Forced candidate, used when NEKO_AUTOTUNE pins the kstep variant */
static int neko_eb_env()
{
  const char *v = getenv("NEKO_EB");
  int c = (v != NULL) ? atoi(v) : 0;
 
  if (c < 0 || c >= NEKO_EB_CANDIDATES) {
    c = 0;
  }
  return c;
}
 
/* Forced chunk candidate, used when NEKO_AUTOTUNE pins the 1d variant */
static int neko_chunks_env()
{
  const char *v = getenv("NEKO_CHUNKS");
  int c = (v != NULL) ? atoi(v) : 0;
 
  if (c < 0 || c >= NEKO_CHUNKS_CANDIDATES) {
    c = 0;
  }
  return c;
}
 
static int neko_tune_rounds()
{
  const char *v = getenv("NEKO_TUNE_ROUNDS");
  int n = (v != NULL) ? atoi(v) : 3;
 
  return (n < 1) ? 1 : n;
}
 
static int neko_tune_iters()
{
  const char *v = getenv("NEKO_TUNE_ITERS");
  int n = (v != NULL) ? atoi(v) : 100;
 
  return (n < 1) ? 1 : n;
}
 
/* One timed round of LAUNCH at candidate C, min reduced into T[C] */
#define NEKO_TUNE_TIME(T, LAUNCH, LX, C, ITERS)                           \
  do {                                                                        \
    float t_;                                                                 \
    cudaEventRecord(start, stream);                                           \
    for (int i_ = 0; i_ < (ITERS); i_++) { LAUNCH(LX, C); }                   \
    cudaEventRecord(stop, stream);                                            \
    cudaEventSynchronize(stop);                                               \
    cudaEventElapsedTime(&t_, start, stop);                                   \
    if (t_ < (T)[C]) { (T)[C] = t_; }                                         \
  } while (0)
 
#define NEKO_TUNE_BEST(T, BEST, N)                                              \
  do {                                                                        \
    for (int c = 1; c < (N); c++) {                                           \
      if ((T)[c] < (T)[BEST]) { BEST = c; }                                   \
    }                                                                         \
  } while (0)
 
/* Report every measured candidate of both sweeps, not just the winner */
#define NEKO_TUNE_LOG(LX, T1, T2)                                               \
  do {                                                                        \
    for (int c = 0; c < NEKO_CHUNKS_CANDIDATES; c++) {                        \
      if ((T1)[c] >= NEKO_TUNE_INIT) { continue; }                         \
      sprintf(neko_log_buf, "1D    ch=%-4d: %9.2f us/call",                   \
              NEKO_CHUNKS_SEL(LX, c), (T1)[c] * 10.0);                        \
      log_message(neko_log_buf);                                              \
    }                                                                         \
    for (int c = 0; c < NEKO_EB_CANDIDATES; c++) {                            \
      if ((T2)[c] >= NEKO_TUNE_INIT) { continue; }                         \
      sprintf(neko_log_buf, "KSTEP eb=%-4d: %9.2f us/call",                   \
              NEKO_EB_SEL(LX, c), (T2)[c] * 10.0);                            \
      log_message(neko_log_buf);                                              \
    }                                                                         \
  } while (0)
 
#endif // __MATH_ELEM_BLOCK_TUNE_H__