From a5ff98a53789157a6c96e58b2385bb898d688a22 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Tue, 11 Sep 2007 18:01:48 +0200
Subject: [PATCH] Use a different file access method for small inputs.

---
 lib/sorter/TODO     | 4 ----
 lib/sorter/common.h | 5 +++--
 lib/sorter/config.c | 6 ++++--
 lib/sorter/govern.c | 1 +
 lib/sorter/sbuck.c  | 4 ++--
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/lib/sorter/TODO b/lib/sorter/TODO
index 250aa9fb..79a60204 100644
--- a/lib/sorter/TODO
+++ b/lib/sorter/TODO
@@ -11,10 +11,6 @@ o  Log messages should show both original and new size of the data. The speed
    should be probably calculated from the former.
 o  Buffer sizing in shep-export.
 o  Problems with thread stack limit in radix-sorting of arrays.
-o  Prediction of destination buffer in array radix-sorts.
-
-Improvements:
-o  Switching between direct and normal I/O. Should use normal I/O if the input is small enough.
 
 Users of lib/sorter/array.h which might use radix-sorting:
 indexer/chewer.c
diff --git a/lib/sorter/common.h b/lib/sorter/common.h
index a97b4dd2..92423046 100644
--- a/lib/sorter/common.h
+++ b/lib/sorter/common.h
@@ -18,8 +18,8 @@ extern uns sorter_debug, sorter_min_radix_bits, sorter_max_radix_bits, sorter_ad
 extern uns sorter_min_multiway_bits, sorter_max_multiway_bits;
 extern uns sorter_threads, sorter_thread_threshold, sorter_thread_chunk;
 extern uns sorter_radix_threshold;
-extern u64 sorter_bufsize;
-extern struct fb_params sorter_fb_params;
+extern u64 sorter_bufsize, sorter_small_input;
+extern struct fb_params sorter_fb_params, sorter_small_fb_params;
 
 #define SORT_TRACE(x...) do { if (sorter_trace) msg(L_DEBUG, x); } while(0)
 #define SORT_XTRACE(level, x...) do { if (sorter_trace >= level) msg(L_DEBUG, x); } while(0)
@@ -41,6 +41,7 @@ struct sort_context {
   struct fastbuf *out_fb;
   uns hash_bits;
   u64 in_size;
+  struct fb_params *fb_params;
 
   struct mempool *pool;
   clist bucket_list;
diff --git a/lib/sorter/config.c b/lib/sorter/config.c
index d12a65bd..e0927ba8 100644
--- a/lib/sorter/config.c
+++ b/lib/sorter/config.c
@@ -13,7 +13,6 @@
 #include "lib/sorter/common.h"
 
 uns sorter_trace;
-uns sorter_stream_bufsize = 65536;
 u64 sorter_bufsize = 65536;
 uns sorter_debug;
 uns sorter_min_radix_bits;
@@ -26,12 +25,15 @@ uns sorter_thread_threshold = 1048576;
 uns sorter_thread_chunk = 4096;
 uns sorter_radix_threshold = 4096;
 struct fb_params sorter_fb_params;
+struct fb_params sorter_small_fb_params;
+u64 sorter_small_input;
 
 static struct cf_section sorter_config = {
   CF_ITEMS {
     CF_UNS("Trace", &sorter_trace),
-    CF_UNS("StreamBuffer", &sorter_stream_bufsize),
     CF_SECTION("FileAccess", &sorter_fb_params, &fbpar_cf),
+    CF_SECTION("SmallFileAccess", &sorter_fb_params, &fbpar_cf),
+    CF_U64("SmallInput", &sorter_small_input),
     CF_U64("SortBuffer", &sorter_bufsize),
     CF_UNS("Debug", &sorter_debug),
     CF_UNS("MinRadixBits", &sorter_min_radix_bits),
diff --git a/lib/sorter/govern.c b/lib/sorter/govern.c
index 619b351d..5ce88473 100644
--- a/lib/sorter/govern.c
+++ b/lib/sorter/govern.c
@@ -413,6 +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);
diff --git a/lib/sorter/sbuck.c b/lib/sorter/sbuck.c
index bff52d66..1150c9d6 100644
--- a/lib/sorter/sbuck.c
+++ b/lib/sorter/sbuck.c
@@ -69,7 +69,7 @@ sbuck_swap_in(struct sort_bucket *b)
 {
   if (b->flags & SBF_SWAPPED_OUT)
     {
-      b->fb = bopen_file(b->filename, O_RDWR, &sorter_fb_params);	/* FIXME: Something different for small buckets? */
+      b->fb = bopen_file(b->filename, O_RDWR, b->ctx->fb_params);
       if (b->flags & SBF_OPEN_WRITE)
 	bseek(b->fb, 0, SEEK_END);
       bconfig(b->fb, BCONFIG_IS_TEMP_FILE, 1);
@@ -104,7 +104,7 @@ sbuck_write(struct sort_bucket *b)
   else
     {
       ASSERT(!(b->flags & (SBF_OPEN_READ | SBF_DESTROYED)));
-      b->fb = bopen_tmp_file(&sorter_fb_params);
+      b->fb = bopen_tmp_file(b->ctx->fb_params);
       if (sorter_debug & SORT_DEBUG_KEEP_BUCKETS)
 	bconfig(b->fb, BCONFIG_IS_TEMP_FILE, 0);
       b->flags |= SBF_OPEN_WRITE;
-- 
2.39.2