Speed up the session invocation time of "flattened" format dumpfiles

created by the makedumpfile(8) facility.  When sorting the blocks of
memory by their intended ELF or compressed kdump file offsets, the
patch replaces the bubble-sort method that is currently used with an
insertion sort method.
([email protected])

makedumpfile.c

@@ -56,8 +56,10 @@ store_flat_data_array(char *file, struct flat_data **fda)
 {
 	int			result = FALSE, fd;
 	int64_t			offset_fdh;
+	int64_t			offset_report = 0;
 	unsigned long long	num_allocated = 0;
 	unsigned long long	num_stored    = 0;
+	unsigned long long	sort_idx;
 	unsigned long long	size_allocated;
 	struct flat_data	*ptr = NULL, *cur, *new;
 	struct makedumpfile_data_header	fdh;
@@ -100,11 +102,34 @@ store_flat_data_array(char *file, struct flat_data **fda)
 			break;
 		}
 		cur = ptr + num_stored;
+		sort_idx = num_stored;
+		while (sort_idx) {
+			new = ptr + --sort_idx;
+			if (new->off_rearranged >= fdh.offset) {
+				cur->off_flattened = new->off_flattened;
+				cur->off_rearranged = new->off_rearranged;
+				cur->buf_size = new->buf_size;
+				cur = new;
+			} else {
+				if (CRASHDEBUG(1) && sort_idx + 1 != num_stored) {
+					fprintf(fp,
+						"makedumpfile: Moved from %lld to %lld\n",
+						num_stored, sort_idx + 1);
+				}
+				break;
+			}
+		}
 		cur->off_flattened  = offset_fdh + sizeof(fdh);
 		cur->off_rearranged = fdh.offset;
 		cur->buf_size       = fdh.buf_size;
 		num_stored++;
 
+		if (CRASHDEBUG(1) && (fdh.offset >> 30) > (offset_report >> 30)) {
+			fprintf(fp, "makedumpfile: At %lld GiB\n",
+			      (ulonglong)(fdh.offset >> 30));
+			offset_report = fdh.offset;
+		}
+
 		/* seek for next makedumpfile_data_header. */
 		if (lseek(fd, fdh.buf_size, SEEK_CUR) < 0) {
 			error(INFO, "%s: seek error (flat format)\n", file);
@@ -121,35 +146,6 @@ store_flat_data_array(char *file, struct flat_data **fda)
 	return num_stored;
 }
 
-static void
-sort_flat_data_array(struct flat_data **fda, unsigned long long num_fda)
-{
-	unsigned long long	i, j;
-	struct flat_data	tmp, *cur_i, *cur_j;
-
-	for (i = 0; i < num_fda - 1; i++) {
-		for (j = i + 1; j < num_fda; j++) {
-			cur_i = *fda + i;
-			cur_j = *fda + j;
-
-			if (cur_i->off_rearranged < cur_j->off_rearranged)
-				continue;
-
-			tmp.off_flattened  = cur_i->off_flattened;
-			tmp.off_rearranged = cur_i->off_rearranged;
-			tmp.buf_size       = cur_i->buf_size;
-
-			cur_i->off_flattened  = cur_j->off_flattened;
-			cur_i->off_rearranged = cur_j->off_rearranged;
-			cur_i->buf_size       = cur_j->buf_size;
-
-			cur_j->off_flattened  = tmp.off_flattened;
-			cur_j->off_rearranged = tmp.off_rearranged;
-			cur_j->buf_size       = tmp.buf_size;
-		}
-	}
-}
-
 static int
 read_all_makedumpfile_data_header(char *file)
 {
@@ -161,8 +157,6 @@ read_all_makedumpfile_data_header(char *file)
 	if (retval < 0)
 		return FALSE;
 
-	sort_flat_data_array(&fda, num);
-
 	afd.num_array = num;
 	afd.array     = fda;