[ewg] Interop test failure using OFED-3.5 RC4

[Marciniszyn, Mike]

This is definitely a perftest bug.

This is a significant re-write of these utilities and this bug is a regression in the routine ctx_set_out_reads().

In 1.4 the code is this:
/******************************************************************************
 *
 ******************************************************************************/
static int ctx_set_out_reads(struct ibv_context *context,int num_user_reads) {


        int max_reads;

        max_reads = (is_dev_hermon(context) == HERMON) ? MAX_OUT_READ_HERMON : MAX_OUT_READ;<---------------

        if (num_user_reads > max_reads) {
                fprintf(stderr," Number of outstanding reads is above max = %d\n",max_reads);
                fprintf(stderr," Changing to that max value\n");
                num_user_reads = max_reads;
        }
        else if (num_user_reads <= 0) {
                num_user_reads = max_reads;
        }

        return num_user_reads;
}

The new 2.0 code is:
/******************************************************************************
 *
 ******************************************************************************/
static int ctx_set_out_reads(struct ibv_context *context,int num_user_reads) {


        int max_reads;

        Device ib_fdev = ib_dev_name(context);

        switch (ib_fdev) {
                case CONNECTIB : ;
                case CONNECTX3 : ;
                case CONNECTX2 : ;
                case CONNECTX : max_reads = MAX_OUT_READ_HERMON; break;
                case LEGACY : max_reads = MAX_OUT_READ; break;
                default : max_reads = 0; <--------------------
        }

        if (num_user_reads > max_reads) {
                printf(RESULT_LINE);
                fprintf(stderr," Number of outstanding reads is above max = %d\n",max_reads);
                fprintf(stderr," Changing to that max value\n");
                num_user_reads = max_reads;
        }
        else if (num_user_reads <= 0) {
                num_user_reads = max_reads;
        }

        return num_user_reads;
}

The old code will return MAX_OUT_READ, while the new code for any other HCAs (qib and probably others), will return 0.

I have a patch that works, while preserving the desired hardcoded values for "known/legacy" devices:
+
+/******************************************************************************
+ *
+ ******************************************************************************/
+static int device_max_reads(struct ibv_context *context) {
+       struct ibv_device_attr attr;
+       int ret = 0;
+
+       if (!ibv_query_device(context,&attr)) {
+               ret = attr.max_qp_rd_atom;
+       }
+       return ret;
+}
+
 /******************************************************************************
  *
  ******************************************************************************/
@@ -496,7 +510,7 @@ static int ctx_set_out_reads(struct ibv_
                case CONNECTX2 : ;
                case CONNECTX : max_reads = MAX_OUT_READ_HERMON; break;
                case LEGACY : max_reads = MAX_OUT_READ; break;
-               default : max_reads = 0;
+               default : max_reads = device_max_reads(context);
        }

        if (num_user_reads > max_reads) {

I'm curious why the old and new code used hardcoded values?

Mike