From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37863) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1chJxV-0006Hp-Sh for qemu-devel@nongnu.org; Fri, 24 Feb 2017 12:47:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1chJxU-0004uP-Ty for qemu-devel@nongnu.org; Fri, 24 Feb 2017 12:47:09 -0500 From: Jeff Cody Date: Fri, 24 Feb 2017 12:46:59 -0500 Message-Id: <20170224174700.30816-3-jcody@redhat.com> In-Reply-To: <20170224174700.30816-1-jcody@redhat.com> References: <20170224174700.30816-1-jcody@redhat.com> Subject: [Qemu-devel] [PULL 2/3] block/nfs: try to avoid the bounce buffer in pwritev List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: peter.maydell@linaro.org, jcody@redhat.com, qemu-devel@nongnu.org From: Peter Lieven if the passed qiov contains exactly one iov we can pass the buffer directly. Signed-off-by: Peter Lieven Reviewed-by: Jeff Cody Message-id: 1487349541-10201-3-git-send-email-pl@kamp.de Signed-off-by: Jeff Cody --- block/nfs.c | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-) diff --git a/block/nfs.c b/block/nfs.c index c11c4c9..ffb54be 100644 --- a/block/nfs.c +++ b/block/nfs.c @@ -302,30 +302,39 @@ static int coroutine_fn nfs_co_pwritev(BlockDriverState *bs, uint64_t offset, NFSClient *client = bs->opaque; NFSRPC task; char *buf = NULL; + bool my_buffer = false; nfs_co_init_task(bs, &task); - buf = g_try_malloc(bytes); - if (bytes && buf == NULL) { - return -ENOMEM; + if (iov->niov != 1) { + buf = g_try_malloc(bytes); + if (bytes && buf == NULL) { + return -ENOMEM; + } + qemu_iovec_to_buf(iov, 0, buf, bytes); + my_buffer = true; + } else { + buf = iov->iov[0].iov_base; } - qemu_iovec_to_buf(iov, 0, buf, bytes); - if (nfs_pwrite_async(client->context, client->fh, offset, bytes, buf, nfs_co_generic_cb, &task) != 0) { + if (my_buffer) { + g_free(buf); + } + return -ENOMEM; + } + + nfs_set_events(client); + while (!task.complete) { + qemu_coroutine_yield(); + } + + if (my_buffer) { g_free(buf); - return -ENOMEM; } - nfs_set_events(client); - while (!task.complete) { - qemu_coroutine_yield(); - } - - g_free(buf); - if (task.ret != bytes) { return task.ret < 0 ? task.ret : -EIO; } -- 2.9.3