[ofw] [IPOIB_NDIS6_CM] enhance wc linking loop performance by removing array index calculations

[Smith, Stan]

Hello,

While reading IPOIB code I noticed a minor speed enhancement in CQ callback routines.
When linking WC (work complete) items into a list, by removing the array index calculations in favor of pointer arithmetic the loop will execute slightly faster.

Worth a commit?

stan.

--- A/ulp/ipoib_NDIS6_CM/kernel/ipoib_endpoint.cpp      Wed Aug 04 10:30:43 2010
+++ B/ulp/ipoib_NDIS6_CM/kernel/ipoib_endpoint.cpp      Wed Aug 04 10:28:59 2010
@@ -888,9 +888,10 @@
                p_port->p_adapter->p_ifc->modify_qp( p_endpt->conn.h_send_qp, &mod_attr );
                p_port->p_adapter->p_ifc->modify_qp( p_endpt->conn.h_recv_qp, &mod_attr );

-               for( i = 0; i < MAX_RECV_WC; i++ )
-                       wc[i].p_next = &wc[i + 1];
-               wc[MAX_RECV_WC - 1].p_next = NULL;
+       for( p_free_wc=wc; p_free_wc < &wc[MAX_RECV_WC]; p_free_wc++ )
+               p_free_wc->p_next = p_free_wc + 1;
+
+       (--p_free_wc)->p_next = NULL;

                do
                {

--- A/ulp/ipoib_NDIS6_CM/kernel/ipoib_port.cpp  Wed Aug 04 10:29:33 2010
+++ B/ulp/ipoib_NDIS6_CM/kernel/ipoib_port.cpp  Wed Aug 04 10:28:31 2010
@@ -1987,7 +1987,6 @@
        ib_wc_t                         wc[MAX_RECV_WC], *p_free, *p_wc;
        int32_t                         NBL_cnt, recv_cnt = 0, shortage, discarded;
        cl_qlist_t                      done_list, bad_list;
-       size_t                          i;
        ULONG                           recv_complete_flags = 0;
        BOOLEAN                         res;

@@ -2017,9 +2016,11 @@
        cl_qlist_init( &bad_list );

        ipoib_port_ref( p_port, ref_recv_cb );
-       for( i = 0; i < MAX_RECV_WC; i++ )
-               wc[i].p_next = &wc[i + 1];
-       wc[MAX_RECV_WC - 1].p_next = NULL;
+
+       for( p_free=wc; p_free < &wc[MAX_RECV_WC]; p_free++ )
+               p_free->p_next = p_free + 1;
+
+       (--p_free)->p_next = NULL;

        /*
         * We'll be accessing the endpoint map so take a reference
@@ -5769,7 +5770,6 @@
        cl_qlist_t                      done_list;
        ipoib_endpt_t           *p_endpt;
        ip_stat_sel_t           type;
-       size_t                          i;
        NET_BUFFER                      *p_netbuffer = NULL;
        ipoib_send_NB_SG        *s_buf;

@@ -5798,9 +5798,10 @@
        //cl_qlist_check_validity(&p_port->send_mgr.pending_list);
        ipoib_port_ref( p_port, ref_send_cb );

-       for( i = 0; i < MAX_SEND_WC; i++ )
-               wc[i].p_next = &wc[i + 1];
-       wc[MAX_SEND_WC - 1].p_next = NULL;
+       for( p_free=wc; p_free < &wc[MAX_SEND_WC]; p_free++ )
+               p_free->p_next = p_free + 1;
+
+       (--p_free)->p_next = NULL;

        do
        {