Make the sbcast buffer large right from the start to avoid realloc calls.

src/common/pack.c

@@ -49,6 +49,7 @@
  */
 strong_alias(create_buf,	slurm_create_buf);
 strong_alias(free_buf,		slurm_free_buf);
+strong_alias(grow_buf,		slurm_grow_buf);
 strong_alias(init_buf,		slurm_init_buf);
 strong_alias(xfer_buf_data,	slurm_xfer_buf_data);
 strong_alias(pack_time,		slurm_pack_time);
@@ -96,6 +97,13 @@ void free_buf(Buf my_buf)
 	xfree(my_buf);
 }
 
+/* Grow a buffer by the specified amount */
+void grow_buf (Buf buffer, int size)
+{
+	buffer->size += size;
+	xrealloc(buffer->head, buffer->size);
+}
+
 /* init_buf - create an empty buffer of the given size */
 Buf init_buf(int size)
 {

src/common/pack.h

@@ -66,6 +66,7 @@ typedef struct slurm_buf * Buf;
 Buf	create_buf (char *data, int size);
 void	free_buf(Buf my_buf);
 Buf	init_buf(int size);
+void    grow_buf (Buf my_buf, int size);
 void	*xfer_buf_data(Buf my_buf);
 
 void	pack_time(time_t val, Buf buffer);

src/common/slurm_protocol_pack.c

@@ -3581,9 +3581,13 @@ _unpack_checkpoint_resp_msg(checkpoint_resp_msg_t **msg_ptr, Buf buffer)
 
 static void _pack_file_bcast(file_bcast_msg_t * msg , Buf buffer )
 {
-	int i;
+	int buf_size = 1024, i;
 	xassert ( msg != NULL );
 
+	for (i=0; i<FILE_BLOCKS; i++)
+		buf_size += msg->block_len[i];
+	grow_buf(buffer, buf_size);
+	
 	pack16 ( msg->block_no, buffer );
 	pack16 ( msg->last_block, buffer );
 	pack16 ( msg->force, buffer );

src/common/slurm_xlator.h

@@ -187,6 +187,7 @@
 /* pack.[ch] functions */
 #define	create_buf		slurm_create_buf
 #define	free_buf		slurm_free_buf
+#define grow_buf		slurm_grow_buf
 #define	init_buf		slurm_init_buf
 #define	xfer_buf_data		slurm_xfer_buf_data
 #define	pack_time		slurm_pack_time

src/sbcast/agent.c

@@ -50,7 +50,7 @@
 #include "src/sbcast/sbcast.h"
 
 #define MAX_RETRIES     10
-#define MAX_THREADS      3	/* These can be huge messages, so
+#define MAX_THREADS      4	/* These can be huge messages, so
 				 * only run MAX_THREADS at one time */
 typedef struct thd {
 	pthread_t thread;	/* thread ID */