From 6d8f1feed063e04d0419c0d895e919a24c7c24d4 Mon Sep 17 00:00:00 2001
From: Chengchang Tang <tangchengchang@huawei.com>
Date: Tue, 8 Nov 2022 20:20:44 +0800
Subject: Perftest: replace rand() with getrandom() during MR buffer
 initialization

rand() has very poor performance in some OS.

ib_send_bw will spend a lot of time during MR initialization when
testing large packects in above scenario.

test has been done:
"""
\#define HUGE_MR_SIZE 2147483647
int main(int argc, char *argv[])
{
        char *a = malloc(HUGE_MR_SIZE * sizeof(char));
        unsigned int i;
        char *tmp = a;
        int ret;

        srand(time(NULL));
        if (a == NULL)
                exit(1);

        if (argc <= 1)
                goto fall_back;

        for (i = HUGE_MR_SIZE; i > 0;) {
                ret = getrandom(tmp, i, 0);
                if (ret < 0)
                        goto fall_back;
                tmp += ret;
                i -= ret;
        }
        goto out;

fall_back:
        for(i = 0; i < HUGE_MR_SIZE; i++)
                a[i] = (char)rand();
out:
        free(a);
        return 0;
}

time ./a.out
real    5m35.033s
user    5m33.546s
sys     0m0.918s

time ./a.out 1

real    0m6.454s
user    0m0.000s
sys     0m6.449s
"""

As shown in the test above, getrandom() has a much better performance,
so replace rand() with it.

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
---
 configure.ac             |  1 +
 src/perftest_resources.c | 31 ++++++++++++++++++++++++++-----
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index 21a17bc..2bbc7fc 100755
--- a/configure.ac
+++ b/configure.ac
@@ -60,6 +60,7 @@ AC_PROG_LIBTOOL
 AC_PROG_RANLIB
 AC_HEADER_STDC
 AC_CHECK_HEADERS([infiniband/verbs.h],,[AC_MSG_ERROR([ibverbs header files not found])])
+AC_CHECK_HEADERS([sys/random.h],,)
 AC_CHECK_LIB([ibverbs], [ibv_get_device_list], [], [AC_MSG_ERROR([libibverbs not found])])
 AC_CHECK_LIB([rdmacm], [rdma_create_event_channel], [], AC_MSG_ERROR([librdmacm-devel not found]))
 AC_CHECK_LIB([ibumad], [umad_init], [LIBUMAD=-libumad], AC_MSG_ERROR([libibumad not found]))
diff --git a/src/perftest_resources.c b/src/perftest_resources.c
index 33db58e..23c31d1 100755
--- a/src/perftest_resources.c
+++ b/src/perftest_resources.c
@@ -22,6 +22,9 @@
 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif
+#ifdef HAVE_SYS_RANDOM_H
+#include <sys/random.h>
+#endif
 #ifdef HAVE_SRD
 #include <infiniband/efadv.h>
 #endif
@@ -1542,12 +1545,33 @@ int create_cqs(struct pingpong_context *ctx, struct perftest_parameters *user_pa
 	return ret;
 }
 
+static void random_data(char *buf, int buff_size)
+{
+	int i;
+#ifdef HAVE_SYS_RANDOM_H
+	char *tmp = buf;
+	int ret;
+
+	for(i = buff_size; i > 0;) {
+		ret = getrandom(tmp, i, 0);
+		if(ret < 0)
+			goto fall_back;
+		tmp += ret;
+		i -= ret;
+	}
+	return;
+fall_back:
+#endif
+	srand(time(NULL));
+	for (i = 0; i < buff_size; i++)
+		buf[i] = (char)rand();
+}
+
 /******************************************************************************
  *
  ******************************************************************************/
 int create_single_mr(struct pingpong_context *ctx, struct perftest_parameters *user_param, int qp_index)
 {
-	int i;
 	int flags = IBV_ACCESS_LOCAL_WRITE;
 
 
@@ -1686,13 +1710,10 @@ int create_single_mr(struct pingpong_context *ctx, struct perftest_parameters *u
 #ifdef HAVE_CUDA
 	if (!user_param->use_cuda) {
 #endif
-		srand(time(NULL));
 		if (user_param->verb == WRITE && user_param->tst == LAT) {
 			memset(ctx->buf[qp_index], 0, ctx->buff_size);
 		} else {
-			for (i = 0; i < ctx->buff_size; i++) {
-				((char*)ctx->buf[qp_index])[i] = (char)rand();
-			}
+			random_data(ctx->buf[qp_index], ctx->buff_size);
 		}
 #ifdef HAVE_CUDA
 	}
-- 
2.34.1