From a9c6ae8f15ecdf5a3ad62076a386c08e983bc472 Mon Sep 17 00:00:00 2001
From: George Bosilca <bosilca@icl.utk.edu>
Date: Fri, 27 Oct 2006 23:16:13 +0000
Subject: [PATCH] Minimize the number of branches, and orce the correct
 prediction for the most usual one. Most of the time we expect the functions
 which allocate requests to succeed.

This commit was SVN r12344.
---
 ompi/mca/pml/ob1/pml_ob1_sendreq.c | 64 ++++++++++++++++--------------
 1 file changed, 34 insertions(+), 30 deletions(-)

diff --git a/ompi/mca/pml/ob1/pml_ob1_sendreq.c b/ompi/mca/pml/ob1/pml_ob1_sendreq.c
index 563a345282..dbb6fda4a8 100644
--- a/ompi/mca/pml/ob1/pml_ob1_sendreq.c
+++ b/ompi/mca/pml/ob1/pml_ob1_sendreq.c
@@ -16,8 +16,10 @@
  * $HEADER$
  */
 
-
 #include "ompi_config.h"
+
+#include "opal/prefetch.h"
+
 #include "ompi/constants.h"
 #include "ompi/mca/pml/pml.h"
 #include "ompi/mca/btl/btl.h"
@@ -470,35 +472,39 @@ int mca_pml_ob1_send_request_start_copy(
     mca_pml_ob1_hdr_t* hdr;
     struct iovec iov;
     unsigned int iov_count;
-    size_t max_data;
+    size_t max_data = size;
     int rc;
 
     /* allocate descriptor */
-    if(0==size)
-        MCA_PML_OB1_DES_ALLOC(bml_btl, descriptor,
-                sizeof(mca_pml_ob1_match_hdr_t));
-    else
-        mca_bml_base_alloc(bml_btl, &descriptor,
-                sizeof(mca_pml_ob1_match_hdr_t) + size);
-    if(NULL == descriptor) {
-        return OMPI_ERR_OUT_OF_RESOURCE;
-    } 
-    segment = descriptor->des_src;
+    if( 0 == size ) {
+        MCA_PML_OB1_DES_ALLOC( bml_btl, descriptor,
+                               sizeof(mca_pml_ob1_match_hdr_t) );
+	if( OPAL_UNLIKELY(NULL == descriptor) ) {
+	    return OMPI_ERR_OUT_OF_RESOURCE;
+	}
+	segment = descriptor->des_src;
+	descriptor->des_cbfunc = mca_pml_ob1_match_completion_cache;
+    } else {
+        mca_bml_base_alloc( bml_btl, &descriptor,
+			    sizeof(mca_pml_ob1_match_hdr_t) + size );
+	if( OPAL_UNLIKELY(NULL == descriptor) ) {
+	    return OMPI_ERR_OUT_OF_RESOURCE;
+	}
+	segment = descriptor->des_src;
 
-    max_data = size;
-    if(size > 0) { 
-        /* pack the data into the supplied buffer */
-        iov.iov_base = (IOVBASE_TYPE*)((unsigned char*)segment->seg_addr.pval + sizeof(mca_pml_ob1_match_hdr_t));
-        iov.iov_len = size;
-        iov_count = 1;
-        if((rc = ompi_convertor_pack(
-                                     &sendreq->req_send.req_convertor,
-                                     &iov,
-                                     &iov_count,
-                                     &max_data)) < 0) {
-            mca_bml_base_free(bml_btl, descriptor);
-            return rc;
-        }
+	/* pack the data into the supplied buffer */
+	iov.iov_base = (IOVBASE_TYPE*)((unsigned char*)segment->seg_addr.pval + sizeof(mca_pml_ob1_match_hdr_t));
+	iov.iov_len = size;
+	iov_count = 1;
+	rc = ompi_convertor_pack( &sendreq->req_send.req_convertor,
+                                  &iov,
+                                  &iov_count,
+                                  &max_data );
+	if( OPAL_UNLIKELY(rc < 0) ) {
+	    mca_bml_base_free(bml_btl, descriptor);
+	    return rc;
+	}
+	descriptor->des_cbfunc = mca_pml_ob1_match_completion_free;
     }
     
     /* build match header */
@@ -530,8 +536,6 @@ int mca_pml_ob1_send_request_start_copy(
     sendreq->req_rdma_offset = max_data;
 
     /* short message */
-    descriptor->des_cbfunc = size?mca_pml_ob1_match_completion_free:
-        mca_pml_ob1_match_completion_cache;
     descriptor->des_flags |= MCA_BTL_DES_FLAGS_PRIORITY;
     descriptor->des_cbdata = sendreq;
 
@@ -542,8 +546,8 @@ int mca_pml_ob1_send_request_start_copy(
 
     /* send */
     rc = mca_bml_base_send(bml_btl, descriptor, MCA_BTL_TAG_PML);
-    if(OMPI_SUCCESS != rc) {
-        if(0==size)
+    if( OPAL_UNLIKELY(OMPI_SUCCESS != rc) ) {
+        if( 0 == size )
             MCA_BML_BASE_BTL_DES_RETURN(bml_btl, descriptor);
         else
             mca_bml_base_free(bml_btl, descriptor );