Merge branch 'tcp_mmap-optmizations'

Eric Dumazet says:

====================
tcp_mmap: optmizations

This series updates tcp_mmap reference tool to use best pratices.

First patch is using madvise(MADV_DONTNEED) to decrease pressure
on the socket lock.

Last patches try to use huge pages when available.
====================
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Arjun Roy <arjunroy@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/tcp_mmap.c

@@ -123,6 +123,28 @@ void hash_zone(void *zone, unsigned int length)
 #define ALIGN_UP(x, align_to)	(((x) + ((align_to)-1)) & ~((align_to)-1))
 #define ALIGN_PTR_UP(p, ptr_align_to)	((typeof(p))ALIGN_UP((unsigned long)(p), ptr_align_to))
 
+
+static void *mmap_large_buffer(size_t need, size_t *allocated)
+{
+	void *buffer;
+	size_t sz;
+
+	/* Attempt to use huge pages if possible. */
+	sz = ALIGN_UP(need, map_align);
+	buffer = mmap(NULL, sz, PROT_READ | PROT_WRITE,
+		      MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
+
+	if (buffer == (void *)-1) {
+		sz = need;
+		buffer = mmap(NULL, sz, PROT_READ | PROT_WRITE,
+			      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+		if (buffer != (void *)-1)
+			fprintf(stderr, "MAP_HUGETLB attempt failed, look at /sys/kernel/mm/hugepages for optimal performance\n");
+	}
+	*allocated = sz;
+	return buffer;
+}
+
 void *child_thread(void *arg)
 {
 	unsigned long total_mmap = 0, total = 0;
@@ -135,6 +157,7 @@ void *child_thread(void *arg)
 	void *addr = NULL;
 	double throughput;
 	struct rusage ru;
+	size_t buffer_sz;
 	int lu, fd;
 
 	fd = (int)(unsigned long)arg;
@@ -142,9 +165,9 @@ void *child_thread(void *arg)
 	gettimeofday(&t0, NULL);
 
 	fcntl(fd, F_SETFL, O_NDELAY);
-	buffer = malloc(chunk_size);
-	if (!buffer) {
-		perror("malloc");
+	buffer = mmap_large_buffer(chunk_size, &buffer_sz);
+	if (buffer == (void *)-1) {
+		perror("mmap");
 		goto error;
 	}
 	if (zflg) {
@@ -179,6 +202,10 @@ void *child_thread(void *arg)
 				total_mmap += zc.length;
 				if (xflg)
 					hash_zone(addr, zc.length);
+				/* It is more efficient to unmap the pages right now,
+				 * instead of doing this in next TCP_ZEROCOPY_RECEIVE.
+				 */
+				madvise(addr, zc.length, MADV_DONTNEED);
 				total += zc.length;
 			}
 			if (zc.recv_skip_hint) {
@@ -230,7 +257,7 @@ void *child_thread(void *arg)
 				ru.ru_nvcsw);
 	}
 error:
-	free(buffer);
+	munmap(buffer, buffer_sz);
 	close(fd);
 	if (zflg)
 		munmap(raddr, chunk_size + map_align);
@@ -347,6 +374,7 @@ int main(int argc, char *argv[])
 	uint64_t total = 0;
 	char *host = NULL;
 	int fd, c, on = 1;
+	size_t buffer_sz;
 	char *buffer;
 	int sflg = 0;
 	int mss = 0;
@@ -437,8 +465,8 @@ int main(int argc, char *argv[])
 		}
 		do_accept(fdlisten);
 	}
-	buffer = mmap(NULL, chunk_size, PROT_READ | PROT_WRITE,
-			      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	buffer = mmap_large_buffer(chunk_size, &buffer_sz);
 	if (buffer == (char *)-1) {
 		perror("mmap");
 		exit(1);
@@ -484,6 +512,6 @@ int main(int argc, char *argv[])
 		total += wr;
 	}
 	close(fd);
-	munmap(buffer, chunk_size);
+	munmap(buffer, buffer_sz);
 	return 0;
 }