From 19a7adca7a6c9bf7061a384d7e9d9b13676a1a88 Mon Sep 17 00:00:00 2001
From: Tim Dettmers <tim.dettmers@gmail.com>
Date: Sun, 11 Sep 2022 11:55:09 -0700
Subject: Fixed 2^31 max size issue for cpu blockwise quant.

---
 csrc/cpu_ops.cpp | 89 +++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 52 insertions(+), 37 deletions(-)

(limited to 'csrc/cpu_ops.cpp')

diff --git a/csrc/cpu_ops.cpp b/csrc/cpu_ops.cpp
index 89de52d..303e8ed 100644
--- a/csrc/cpu_ops.cpp
+++ b/csrc/cpu_ops.cpp
@@ -4,54 +4,69 @@
 
 using namespace BinSearch;
 
-void dequantize_cpu(float *code, unsigned char *A, float *absmax, float *out, int n) {
-    for (int block_idx = 0; block_idx < n; block_idx += BLOCK_SIZE) {
-        int valid_items = n - block_idx >= BLOCK_SIZE ? BLOCK_SIZE : n - block_idx;
-        int block_end = block_idx + valid_items;
-        for (int i = block_idx; i < block_end; i++)
-            out[i] = code[A[i]] * absmax[block_idx / BLOCK_SIZE];
+void dequantize_cpu(float *code, unsigned char *A, float *absmax, float *out, long long blocksize, long long n) {
+    for (long long block_idx = 0; block_idx < n; block_idx += blocksize) {
+        long long valid_items = n - block_idx >= blocksize ? blocksize : n - block_idx;
+        long long block_end = block_idx + valid_items;
+        for (long long i = block_idx; i < block_end; i++)
+            out[i] = code[A[i]] * absmax[block_idx / blocksize];
     }
 }
 
-void quantize_cpu(float *code, float *A, float *absmax, unsigned char *out, int n) {
+void quantize_cpu(float *code, float *A, float *absmax, unsigned char *out, long long blocksize, long long n)
+{
 
     // the default code is has range [-0.993, 1.0] which can cause an error in the binary search algorithm used below
     code[0] = -1.0f;
 
-    int num_blocks = n / BLOCK_SIZE;
-    num_blocks += n % BLOCK_SIZE == 0 ? 0 : 1;
-
-    pthread_t *threads = (pthread_t *) malloc(sizeof(pthread_t) * num_blocks);
-    struct quantize_block_args **args = (quantize_block_args **) malloc(num_blocks * sizeof(quantize_block_args *));
-
-    for (int i = 0; i < num_blocks; i++)
-        args[i] = (quantize_block_args *) malloc(sizeof(quantize_block_args));
+    long long num_blocks = n / blocksize;
+    num_blocks += n % blocksize == 0 ? 0 : 1;
 
     const uint32 elements_code = 256;
     BinAlgo<Scalar, float, Direct2> bin_searcher(code, elements_code);
 
-    for (int block_idx = 0; block_idx < n; block_idx += BLOCK_SIZE) {
-        int valid_items = n - block_idx >= BLOCK_SIZE ? BLOCK_SIZE : n - block_idx;
-        int block_end = block_idx + valid_items;
-
-        struct quantize_block_args *arg = args[block_idx / BLOCK_SIZE];
-        arg->bin_searcher = &bin_searcher;
-        arg->code = code;
-        arg->A = A;
-        arg->absmax = absmax;
-        arg->out = out;
-        arg->block_end = block_end;
-        arg->block_idx = block_idx;
-        arg->threadidx = block_idx / BLOCK_SIZE;
-
-        pthread_create(&threads[block_idx / BLOCK_SIZE], NULL, &quantize_block, (void *) arg);
-    }
+    int thread_wave_size = 256;
+    // we chunk the thresds into waves of 256 since the max limit is
+    // between 16k and 64k on Linux (we reach this when running BLOOM-176B with a large batch size)
+    for(long long offset = 0; offset < num_blocks; offset+=thread_wave_size)
+    {
+      pthread_t *threads = (pthread_t *) malloc(sizeof(pthread_t) * thread_wave_size);
+
+      struct quantize_block_args **args = (quantize_block_args **) malloc(thread_wave_size * sizeof(quantize_block_args *));
+
+      for(long long i = 0; i < thread_wave_size; i++)
+          args[i] = (quantize_block_args *) malloc(sizeof(quantize_block_args));
 
-    for (int i = 0; i < num_blocks; i++)
-        int err = pthread_join(threads[i], NULL);
+      int chunks_processed = 0;
+      for(long long block_idx = offset*blocksize; block_idx < n; block_idx += blocksize)
+      {
+          long long valid_items = n - block_idx >= blocksize ? blocksize : n - block_idx;
+          long long block_end = block_idx + valid_items;
+
+          struct quantize_block_args *arg = args[chunks_processed];
+          arg->bin_searcher = &bin_searcher;
+          arg->code = code;
+          arg->A = A;
+          arg->absmax = absmax;
+          arg->out = out;
+          arg->block_end = block_end;
+          arg->block_idx = block_idx;
+          arg->threadidx = block_idx / blocksize;
+          arg->blocksize = blocksize;
+
+          pthread_create(&threads[chunks_processed], NULL, &quantize_block, (void *) arg);
+          chunks_processed += 1;
+          if(chunks_processed == thread_wave_size){ break; }
+      }
+
+      for (int i = 0; i < thread_wave_size; i++)
+          int err = pthread_join(threads[i], NULL);
+      
+      free(threads);
+      for (int i = 0; i < thread_wave_size; i++)
+          free(args[i]);
+      free(args);
+
+    }
 
-    free(threads);
-    for (int i = 0; i < num_blocks; i++)
-        free(args[i]);
-    free(args);
 }
-- 
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