initial

.gitignore

+hugepage_uring_0copy_perf

Makefile

+programs = hugepage_uring_0copy_perf
+
+sources = main.c
+
+CC = gcc
+LDFLAGS = -luring
+
+all: $(programs)
+
+$(programs): $(sources)
+	$(CC) $(CFLAGS) $< -o $@ $(LDFLAGS)
+
+check: $(programs)
+	./hugepage_uring_0copy_perf 1
+
+.PHONY: check

main.c

+/*
+ * simple demo to show long execution times of mmap of 1GB huge pages and
+ * io_uring configuration for zero copy
+ *
+ * March 2022, Nils Goroll <slink@uplex.de>
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <liburing.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include <sys/mman.h>
+#include <linux/mman.h>
+
+/* BEGIN from varnish-cache */
+#define AZ(foo) do { assert((foo) == 0); } while (0)
+#define AN(foo) do { assert((foo) != 0); } while (0)
+
+static double
+VTIM_mono(void)
+{
+	struct timespec ts;
+
+	AZ(clock_gettime(CLOCK_MONOTONIC, &ts));
+	return (ts.tv_sec + 1e-9 * ts.tv_nsec);
+}
+/* END from varnish-cache */
+
+#define ptime(t, d, x) printf(x "\t%.6fs\n", t[d] - t[d - 1])
+
+static void
+usage(const char *name)
+{
+	printf("Usage: %s <gb>\n\t<gr> is gigabytes to mmap()\n", name);
+	exit(1);
+}
+
+static int
+register_buffers(struct io_uring *ring, void *base, unsigned long gb)
+{
+	unsigned u, n = gb + 1;
+	struct iovec iov[n];
+	const size_t sz = (size_t)1<<30;
+	uintptr_t p;
+
+	memset(iov, 0, sizeof iov);
+
+	p = (uintptr_t)base;
+
+	for (u = 0; u < gb ; u++) {
+		iov[u].iov_base = (void *)p;
+		iov[u].iov_len = sz;
+		p += sz;
+	}
+
+	return (io_uring_register_buffers(ring, iov, gb));
+}
+
+int
+main(int argc, char **argv)
+{
+	double t[5];
+	unsigned long gb;
+	char *p;
+	void *base;
+
+	struct io_uring_probe *probe;
+	struct io_uring ring[1];
+
+	if (argc != 2)
+		usage(argv[0]);
+
+	gb = strtoul(argv[1], &p, 10);
+	if (p == argv[1] || *p != '\0')
+		usage(argv[0]);
+
+	probe = io_uring_get_probe();
+	AN(probe);
+	assert(io_uring_opcode_supported(probe, IORING_OP_READ_FIXED));
+	free(probe);
+
+	AZ(io_uring_queue_init(1024, ring, 0));
+
+	t[0] = VTIM_mono();
+	base = mmap(NULL, (size_t)gb << 30, PROT_READ|PROT_WRITE,
+	    MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED |
+	    MAP_HUGETLB | MAP_HUGE_1GB, -1, 0);
+	t[1] = VTIM_mono();
+	if (base == MAP_FAILED) {
+		fprintf(stderr, "mmap() failed with %s (%d)\n"
+		    "Hint: /sys/kernel/mm/hugepages/"
+		    "hugepages-1048576kB/nr_hugepages\n"
+		    "and ulimit -l must be configured\n",
+		    strerror(errno), errno);
+		exit(1);
+	}
+	assert(base != MAP_FAILED);
+	ptime(t, 1, "mmap()");
+
+	AZ(register_buffers(ring, base, gb));
+	t[2] = VTIM_mono();
+	ptime(t, 2, "io_uring_register_buffers()");
+
+	printf("total\t%.6fs\n", t[2] - t[0]);
+
+	return (0);
+}