From 85df21fe3963f2a70863253ee7445e5fe624c966 Mon Sep 17 00:00:00 2001
From: Andrea Arcangeli <aarcange@redhat.com>
Date: Sat, 1 May 2021 18:11:54 -0400
Subject: [PATCH 1/1] pin_user_pages_fast SMP scalability benchmark

This requires the kernel built with CONFIG_GUP_FAST=y and it must be
run as root it won't be able to open /sys/kernel/debug/gup_test.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
 tests/pin_fast.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 tests/pin_fast.c

diff --git a/tests/pin_fast.c b/tests/pin_fast.c
new file mode 100644
index 0000000..b1e6282
--- /dev/null
+++ b/tests/pin_fast.c
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <assert.h>
+#include <sys/prctl.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+
+/* exercises pin_user_pages_fast, requires a kernel with CONFIG_GUP_TEST=y */
+char *testcase_description = "pin_user_pages_fast SMP scalability benchmark";
+
+static int gup_fd;
+#define NR_PAGES 1024
+#define BUFLEN (getpagesize() * NR_PAGES)
+
+#define GUP_TEST_MAX_PAGES_TO_DUMP		8
+#define PIN_FAST_BENCHMARK	_IOWR('g', 2, struct gup_test)
+
+struct gup_test {
+	__u64 get_delta_usec;
+	__u64 put_delta_usec;
+	__u64 addr;
+	__u64 size;
+	__u32 nr_pages_per_call;
+	__u32 flags;
+	/*
+	 * Each non-zero entry is the number of the page (1-based: first page is
+	 * page 1, so that zero entries mean "do nothing") from the .addr base.
+	 */
+	__u32 which_pages[GUP_TEST_MAX_PAGES_TO_DUMP];
+};
+
+void testcase_prepare(unsigned long nr_tasks)
+{
+	gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+	assert(gup_fd >= 0);
+}
+
+void testcase(unsigned long long *iterations, unsigned long nr)
+{
+	char *p = aligned_alloc(getpagesize()*512, BUFLEN);
+	assert(p);
+	assert(!madvise(p, BUFLEN, MADV_HUGEPAGE));
+	for (int i = 0; i < NR_PAGES; i++)
+		p[getpagesize()*i] = 0;
+
+	struct gup_test gup = {
+		.size = BUFLEN,
+		.addr = (unsigned long)p,
+		.nr_pages_per_call = 1,
+	};
+
+	while (1) {
+		assert(!ioctl(gup_fd, PIN_FAST_BENCHMARK, &gup));
+
+		(*iterations)++;
+	}
+
+	free(p);
+}
+
+void testcase_cleanup(void)
+{
+	assert(!close(gup_fd));
+}