t/io_uring: register single buffer for whole IO region

Rather than register N buffers for depth of N, just allocate a single
contig region and register that as a single buffer. That's more
efficient on the kernel side, as only a single resource need to be
managed.

Should have no functional changes.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/t/io_uring.c b/t/io_uring.c
index 0fa01837bbf5259815dcda19ba18e28e6a197b40..e7e1dd1ba93d84f9960a4dd57c6e7d4288d32bb7 100644 (file)
--- a/t/io_uring.c
+++ b/t/io_uring.c
@@ -398,11 +398,20 @@ static void add_stat(struct submitter *s, int clock_index, int nr)
 
 static int io_uring_register_buffers(struct submitter *s)
 {
+       int ret;
+
        if (do_nop)
                return 0;
 
-       return syscall(__NR_io_uring_register, s->ring_fd,
-                       IORING_REGISTER_BUFFERS, s->iovecs, roundup_pow2(depth));
+       /*
+        * All iovecs are filled in case of readv, but it's all contig
+        * from vec0. Just register a single buffer for all buffers.
+        */
+       s->iovecs[0].iov_len = bs * roundup_pow2(depth);
+       ret = syscall(__NR_io_uring_register, s->ring_fd,
+                       IORING_REGISTER_BUFFERS, s->iovecs, 1);
+       s->iovecs[0].iov_len = bs;
+       return ret;
 }
 
 static int io_uring_register_files(struct submitter *s)
@@ -557,7 +566,7 @@ static void init_io(struct submitter *s, unsigned index)
                sqe->opcode = IORING_OP_READ_FIXED;
                sqe->addr = (unsigned long) s->iovecs[index].iov_base;
                sqe->len = bs;
-               sqe->buf_index = index;
+               sqe->buf_index = 0;
        } else if (!vectored) {
                sqe->opcode = IORING_OP_READ;
                sqe->addr = (unsigned long) s->iovecs[index].iov_base;
@@ -1003,10 +1012,12 @@ static int submitter_init(struct submitter *s)
 {
        int i, nr_batch, err;
        static int init_printed;
+       void *mem, *ptr;
        char buf[80];
+
        s->tid = gettid();
-       printf("submitter=%d, tid=%d, file=%s, nfiles=%d, node=%d\n", s->index, s->tid,
-                                                       s->filename, s->nr_files, s->numa_node);
+       printf("submitter=%d, tid=%d, file=%s, nfiles=%d, node=%d\n", s->index,
+                               s->tid, s->filename, s->nr_files, s->numa_node);
 
        set_affinity(s);
 
@@ -1016,14 +1027,11 @@ static int submitter_init(struct submitter *s)
        for (i = 0; i < MAX_FDS; i++)
                s->files[i].fileno = i;
 
-       for (i = 0; i < roundup_pow2(depth); i++) {
-               void *buf;
-
-               buf = allocate_mem(s, bs);
-               if (!buf)
-                       return -1;
-               s->iovecs[i].iov_base = buf;
+       mem = allocate_mem(s, bs * roundup_pow2(depth));
+       for (i = 0, ptr = mem; i < roundup_pow2(depth); i++) {
+               s->iovecs[i].iov_base = ptr;
                s->iovecs[i].iov_len = bs;
+               ptr += bs;
        }
 
        if (use_sync) {