X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=sidebyside;f=lib%2Fsorter%2Fgovern.c;h=43b1668846fb975c1fb06fdfe415bb38df328586;hb=dcbe7f152cd2baecd878d8df740d3007357e5d26;hp=6b4dc696ca06de80d4bce4e3c6067f99133fa647;hpb=7119957a2df57af617f432dd429e1d6ae5cbe0fd;p=libucw.git

diff --git a/lib/sorter/govern.c b/lib/sorter/govern.c
index 6b4dc696..43b16688 100644
--- a/lib/sorter/govern.c
+++ b/lib/sorter/govern.c
@@ -48,15 +48,20 @@ sorter_presort(struct sort_context *ctx, struct sort_bucket *in, struct sort_buc
   sorter_alloc_buf(ctx);
   if (in->flags & SBF_CUSTOM_PRESORT)
     {
+      /*
+       *  The trick with automatic joining, which we use for the normal presorter,
+       *  is not necessary with the custom presorter, because the custom presorter
+       *  is never called in the middle of the sorted data.
+       */
       struct fastbuf *f = sbuck_write(out);
       out->runs++;
-      return ctx->custom_presort(f, ctx->big_buf, ctx->big_buf_size);	// FIXME: out_only optimization?
+      return ctx->custom_presort(f, ctx->big_buf, ctx->big_buf_size);
     }
   return ctx->internal_sort(ctx, in, out, out_only);
 }
 
-static inline struct sort_bucket *
-sbuck_join_to(struct sort_bucket *b)
+static struct sort_bucket *
+sbuck_join_to(struct sort_bucket *b, sh_off_t *sizep)
 {
   if (sorter_debug & SORT_DEBUG_NO_JOIN)
     return NULL;
@@ -65,9 +70,30 @@ sbuck_join_to(struct sort_bucket *b)
   if (!(out->flags & SBF_FINAL))
     return NULL;
   ASSERT(out->runs == 1);
+  *sizep = sbuck_size(out);
   return out;
 }
 
+static sh_off_t
+sbuck_ins_or_join(struct sort_bucket *b, cnode *list_pos, struct sort_bucket *join, sh_off_t join_size)
+{
+  if (join)
+    {
+      if (b)
+	sbuck_drop(b);
+      ASSERT(join->runs == 2);
+      join->runs--;
+      return sbuck_size(join) - join_size;
+    }
+  else if (b)
+    {
+      clist_insert_after(&b->n, list_pos);
+      return sbuck_size(b);
+    }
+  else
+    return 0;
+}
+
 static void
 sorter_join(struct sort_bucket *b)
 {
@@ -79,7 +105,7 @@ sorter_join(struct sort_bucket *b)
     {
       // The final bucket doesn't have any file associated yet, so replace
       // it with the new bucket.
-      SORT_XTRACE(2, "Replaced final bucket");
+      SORT_XTRACE(3, "Replaced final bucket");
       b->flags |= SBF_FINAL;
       sbuck_drop(join);
     }
@@ -98,7 +124,8 @@ sorter_twoway(struct sort_context *ctx, struct sort_bucket *b)
 {
   struct sort_bucket *ins[3] = { NULL }, *outs[3] = { NULL };
   cnode *list_pos = b->n.prev;
-  struct sort_bucket *join = sbuck_join_to(b);
+  sh_off_t join_size;
+  struct sort_bucket *join = sbuck_join_to(b, &join_size);
 
   if (!(sorter_debug & SORT_DEBUG_NO_PRESORT) || (b->flags & SBF_CUSTOM_PRESORT))
     {
@@ -108,15 +135,8 @@ sorter_twoway(struct sort_context *ctx, struct sort_bucket *b)
       if (!sorter_presort(ctx, b, ins[0], join ? : ins[0]))
 	{
 	  sorter_stop_timer(ctx, &ctx->total_pre_time);
-	  SORT_XTRACE(((b->flags & SBF_SOURCE) ? 1 : 2), "Sorted in memory");
-	  if (join)
-	    {
-	      ASSERT(join->runs == 2);
-	      join->runs--;
-	      sbuck_drop(ins[0]);
-	    }
-	  else
-	    clist_insert_after(&ins[0]->n, list_pos);
+	  sh_off_t size = sbuck_ins_or_join(ins[0], list_pos, join, join_size);
+	  SORT_XTRACE(((b->flags & SBF_SOURCE) ? 1 : 3), "Sorted in memory (%s, %dMB/s)", stk_fsize(size), sorter_speed(ctx, size));
 	  sbuck_drop(b);
 	  return;
 	}
@@ -143,18 +163,15 @@ sorter_twoway(struct sort_context *ctx, struct sort_bucket *b)
   do {
     ++pass;
     sorter_start_timer(ctx);
-    if (ins[0]->runs == 1 && ins[1]->runs == 1 && join)
+    if (ins[0]->runs <= 1 && ins[1]->runs <= 1 && join)
       {
 	// This is guaranteed to produce a single run, so join if possible
-	sh_off_t join_size = sbuck_size(join);
 	outs[0] = join;
 	outs[1] = NULL;
 	ctx->twoway_merge(ctx, ins, outs);
-	ASSERT(join->runs == 2);
-	join->runs--;
-	join_size = sbuck_size(join) - join_size;
+	sh_off_t size = sbuck_ins_or_join(NULL, NULL, join, join_size);
 	sorter_stop_timer(ctx, &ctx->total_ext_time);
-	SORT_TRACE("Mergesort pass %d (final run, %s, %dMB/s)", pass, stk_fsize(join_size), sorter_speed(ctx, join_size));
+	SORT_TRACE("Mergesort pass %d (final run, %s, %dMB/s)", pass, stk_fsize(size), sorter_speed(ctx, size));
 	sbuck_drop(ins[0]);
 	sbuck_drop(ins[1]);
 	return;
@@ -177,31 +194,100 @@ sorter_twoway(struct sort_context *ctx, struct sort_bucket *b)
   clist_insert_after(&ins[0]->n, list_pos);
 }
 
-static uns
-sorter_radix_bits(struct sort_context *ctx, struct sort_bucket *b)
+static void
+sorter_multiway(struct sort_context *ctx, struct sort_bucket *b)
 {
-  if (!b->hash_bits || b->hash_bits < sorter_min_radix_bits ||
-      !ctx->radix_split ||
-      (b->flags & SBF_CUSTOM_PRESORT) ||
-      (sorter_debug & SORT_DEBUG_NO_RADIX))
-    return 0;
+  clist parts;
+  cnode *list_pos = b->n.prev;
+  sh_off_t join_size;
+  struct sort_bucket *join = sbuck_join_to(b, &join_size);
+  uns trace_level = (b->flags & SBF_SOURCE) ? 1 : 3;
 
-  u64 in = sbuck_size(b);
-  u64 mem = ctx->internal_estimate(ctx, b) * 0.8;	// FIXME: Magical factor for hash non-uniformity
-  if (in <= mem)
-    return 0;
+  clist_init(&parts);
+  ASSERT(!(sorter_debug & SORT_DEBUG_NO_PRESORT));
+  SORT_XTRACE(3, "%s", ((b->flags & SBF_CUSTOM_PRESORT) ? "Custom presorting" : "Presorting"));
+  uns cont;
+  uns part_cnt = 0;
+  u64 total_size = 0;
+  sorter_start_timer(ctx);
+  do
+    {
+      struct sort_bucket *p = sbuck_new(ctx);
+      cont = sorter_presort(ctx, b, p, (!part_cnt && join) ? join : p);
+      if (sbuck_have(p))
+	{
+	  part_cnt++;
+	  clist_add_tail(&parts, &p->n);
+	  total_size += sbuck_size(p);
+	  sbuck_swap_out(p);
+	}
+      else
+	sbuck_drop(p);
+    }
+  while (cont);
+  sorter_stop_timer(ctx, &ctx->total_pre_time);
+  sorter_free_buf(ctx);
+  sbuck_drop(b);
+
+  if (part_cnt <= 1)
+    {
+      sh_off_t size = sbuck_ins_or_join(clist_head(&parts), list_pos, (part_cnt ? NULL : join), join_size);
+      SORT_XTRACE(trace_level, "Sorted in memory (%s, %dMB/s)", stk_fsize(size), sorter_speed(ctx, size));
+      return;
+    }
+
+  SORT_TRACE("Multi-way presorting pass (%d parts, %s, %dMB/s)", part_cnt, stk_fsize(total_size), sorter_speed(ctx, total_size));
+
+  uns max_ways = 1 << sorter_max_multiway_bits;
+  struct sort_bucket *ways[max_ways+1];
+  SORT_XTRACE(3, "Starting up to %d-way merge", max_ways);
+  for (;;)
+    {
+      uns n = 0;
+      struct sort_bucket *p;
+      while (n < max_ways && (p = clist_head(&parts)))
+	{
+	  clist_remove(&p->n);
+	  ways[n++] = p;
+	}
+      ways[n] = NULL;
+      ASSERT(n > 1);
+
+      struct sort_bucket *out;
+      if (clist_empty(&parts) && join)
+	out = join;
+      else
+	out = sbuck_new(ctx);
+      sorter_start_timer(ctx);
+      ctx->multiway_merge(ctx, ways, out);
+      sorter_stop_timer(ctx, &ctx->total_ext_time);
+
+      for (uns i=0; i<n; i++)
+	sbuck_drop(ways[i]);
 
-  uns n = sorter_min_radix_bits;
-  while (n < sorter_max_radix_bits && n < b->hash_bits && (in >> n) > mem)
-    n++;
-  return n;
+      if (clist_empty(&parts))
+	{
+	  sh_off_t size = sbuck_ins_or_join((join ? NULL : out), list_pos, join, join_size);
+	  SORT_TRACE("Multi-way merge completed (%d ways, %s, %dMB/s)", n, stk_fsize(size), sorter_speed(ctx, size));
+	  return;
+	}
+      else
+	{
+	  sbuck_swap_out(out);
+	  clist_add_tail(&parts, &out->n);
+	  SORT_TRACE("Multi-way merge pass (%d ways, %s, %dMB/s)", n, F_BSIZE(out), sorter_speed(ctx, sbuck_size(out)));
+	}
+    }
 }
 
 static void
 sorter_radix(struct sort_context *ctx, struct sort_bucket *b, uns bits)
 {
+  // Add more bits if requested and allowed.
+  bits = MIN(bits + sorter_add_radix_bits, sorter_max_radix_bits);
+
   uns nbuck = 1 << bits;
-  SORT_XTRACE(2, "Running radix split on %s with hash %d bits of %d (expecting %s buckets)",
+  SORT_XTRACE(3, "Running radix split on %s with hash %d bits of %d (expecting %s buckets)",
 	      F_BSIZE(b), bits, b->hash_bits, stk_fsize(sbuck_size(b) / nbuck));
   sorter_free_buf(ctx);
   sorter_start_timer(ctx);
@@ -233,12 +319,87 @@ sorter_radix(struct sort_context *ctx, struct sort_bucket *b, uns bits)
   sbuck_drop(b);
 }
 
+static void
+sorter_decide(struct sort_context *ctx, struct sort_bucket *b)
+{
+  // Drop empty buckets
+  if (!sbuck_have(b))
+    {
+      SORT_XTRACE(4, "Dropping empty bucket");
+      sbuck_drop(b);
+      return;
+    }
+
+  // How many bits of bucket size we have to reduce before it fits in the RAM?
+  // (this is insanely large if the input size is unknown, but it serves our purpose)
+  u64 insize = sbuck_size(b);
+  u64 mem = ctx->internal_estimate(ctx, b) * 0.8;	// Magical factor accounting for various non-uniformities
+  uns bits = 0;
+  while ((insize >> bits) > mem)
+    bits++;
+
+  // Calculate the possibilities of radix splits
+  uns radix_bits;
+  if (!ctx->radix_split ||
+      (b->flags & SBF_CUSTOM_PRESORT) ||
+      (sorter_debug & SORT_DEBUG_NO_RADIX))
+    radix_bits = 0;
+  else
+    {
+      radix_bits = MIN(bits, b->hash_bits);
+      radix_bits = MIN(radix_bits, sorter_max_radix_bits);
+      if (radix_bits < sorter_min_radix_bits)
+	radix_bits = 0;
+    }
+
+  // The same for multi-way merges
+  uns multiway_bits;
+  if (!ctx->multiway_merge ||
+      (sorter_debug & SORT_DEBUG_NO_MULTIWAY) ||
+      (sorter_debug & SORT_DEBUG_NO_PRESORT))
+    multiway_bits = 0;
+  else
+    {
+      multiway_bits = MIN(bits, sorter_max_multiway_bits);
+      if (multiway_bits < sorter_min_multiway_bits)
+	multiway_bits = 0;
+    }
+
+  SORT_XTRACE(3, "Decisions: size=%s max=%s runs=%d bits=%d hash=%d -> radix=%d multi=%d",
+	stk_fsize(insize), stk_fsize(mem), b->runs, bits, b->hash_bits,
+	radix_bits, multiway_bits);
+
+  // If the input already consists of a single run, just join it
+  if (b->runs)
+    return sorter_join(b);
+
+  // If everything fits in memory, the 2-way strategy will sort it in memory
+  if (!bits)
+    return sorter_twoway(ctx, b);
+
+  // If we can reduce everything in one pass, do so and prefer radix splits
+  if (radix_bits == bits)
+    return sorter_radix(ctx, b, radix_bits);
+  if (multiway_bits == bits)
+    return sorter_multiway(ctx, b);
+
+  // Otherwise, reduce as much as possible and again prefer radix splits
+  if (radix_bits)
+    return sorter_radix(ctx, b, radix_bits);
+  if (multiway_bits)
+    return sorter_multiway(ctx, b);
+
+  // Fall back to 2-way strategy if nothing else applies
+  return sorter_twoway(ctx, b);
+}
+
 void
 sorter_run(struct sort_context *ctx)
 {
   ctx->pool = mp_new(4096);
   clist_init(&ctx->bucket_list);
   sorter_prepare_buf(ctx);
+  asort_start_threads(0);
 
   // Create bucket containing the source
   struct sort_bucket *bin = sbuck_new(ctx);
@@ -252,6 +413,7 @@ sorter_run(struct sort_context *ctx)
   bin->hash_bits = ctx->hash_bits;
   clist_add_tail(&ctx->bucket_list, &bin->n);
   SORT_XTRACE(2, "Input size: %s, %d hash bits", F_BSIZE(bin), bin->hash_bits);
+  ctx->fb_params = (bin->size < sorter_small_input) ? &sorter_small_fb_params : &sorter_fb_params;
 
   // Create bucket for the output
   struct sort_bucket *bout = sbuck_new(ctx);
@@ -262,25 +424,17 @@ sorter_run(struct sort_context *ctx)
   bout->runs = 1;
   clist_add_head(&ctx->bucket_list, &bout->n);
 
+  // Repeatedly sort buckets
   struct sort_bucket *b;
-  uns bits;
   while (bout = clist_head(&ctx->bucket_list), b = clist_next(&ctx->bucket_list, &bout->n))
-    {
-      SORT_XTRACE(2, "Next block: %s, %d hash bits", F_BSIZE(b), b->hash_bits);
-      if (!sbuck_have(b))
-	sbuck_drop(b);
-      else if (b->runs == 1)
-	sorter_join(b);
-      else if (bits = sorter_radix_bits(ctx, b))
-	sorter_radix(ctx, b, bits);
-      else
-	sorter_twoway(ctx, b);
-    }
+    sorter_decide(ctx, b);
 
+  asort_stop_threads();
   sorter_free_buf(ctx);
   sbuck_write(bout);		// Force empty bucket to a file
   SORT_XTRACE(2, "Final size: %s", F_BSIZE(bout));
   SORT_XTRACE(2, "Final timings: %.3fs external sorting, %.3fs presorting, %.3fs internal sorting",
 	      ctx->total_ext_time/1000., ctx->total_pre_time/1000., ctx->total_int_time/1000.);
   ctx->out_fb = sbuck_read(bout);
+  mp_delete(ctx->pool);
 }