selftests: net: tcp_mmap: Use huge pages in send path

There are significant gains using huge pages when
available, as shown in [1].

This patch adds mmap_large_buffer() and uses it
in client side (tx path of this reference tool)

Following patch will use the feature for server side.

[1] https://patchwork.ozlabs.org/project/netdev/patch/20200820154359.1806305-1-edumazet@google.com/

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/tools/testing/selftests/net/tcp_mmap.c b/tools/testing/selftests/net/tcp_mmap.c
index 59ec0b59f7b76ff75685bd96901d8237e0665b2b..ca2618f3e7a12ab6863665f465dea2e8d469131b 100644 (file)
--- a/tools/testing/selftests/net/tcp_mmap.c
+++ b/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;
@@ -351,6 +373,7 @@ 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;
@@ -441,8 +464,8 @@ 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);
@@ -488,6 +511,6 @@ int main(int argc, char *argv[])
                total += wr;
        }
        close(fd);
-       munmap(buffer, chunk_size);
+       munmap(buffer, buffer_sz);
        return 0;
 }