From 51b19ebe4320f3dcd93cea71235c1219318ddfd2 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 4 Feb 2016 16:26:51 +0200 Subject: virtio: move allocation to virtqueue_pop/vring_pop The return code of virtqueue_pop/vring_pop is unused except to check for errors or 0. We can thus easily move allocation inside the functions and just return a pointer to the VirtQueueElement. The advantage is that we will be able to allocate only the space that is needed for the actual size of the s/g list instead of the full VIRTQUEUE_MAX_SIZE items. Currently VirtQueueElement takes about 48K of memory, and this kind of allocation puts a lot of stress on malloc. By cutting the size by two or three orders of magnitude, malloc can use much more efficient algorithms. The patch is pretty large, but changes to each device are testable more or less independently. Splitting it would mostly add churn. Signed-off-by: Paolo Bonzini Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Cornelia Huck --- hw/input/virtio-input.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) (limited to 'hw/input/virtio-input.c') diff --git a/hw/input/virtio-input.c b/hw/input/virtio-input.c index f12ed8a504..5061f4cf7a 100644 --- a/hw/input/virtio-input.c +++ b/hw/input/virtio-input.c @@ -17,7 +17,7 @@ void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event) { - VirtQueueElement elem; + VirtQueueElement *elem; unsigned have, need; int i, len; @@ -50,14 +50,16 @@ void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event) /* ... and finally pass them to the guest */ for (i = 0; i < vinput->qindex; i++) { - if (!virtqueue_pop(vinput->evt, &elem)) { + elem = virtqueue_pop(vinput->evt, sizeof(VirtQueueElement)); + if (!elem) { /* should not happen, we've checked for space beforehand */ fprintf(stderr, "%s: Huh? No vq elem available ...\n", __func__); return; } - len = iov_from_buf(elem.in_sg, elem.in_num, + len = iov_from_buf(elem->in_sg, elem->in_num, 0, vinput->queue+i, sizeof(virtio_input_event)); - virtqueue_push(vinput->evt, &elem, len); + virtqueue_push(vinput->evt, elem, len); + g_free(elem); } virtio_notify(VIRTIO_DEVICE(vinput), vinput->evt); vinput->qindex = 0; @@ -73,17 +75,23 @@ static void virtio_input_handle_sts(VirtIODevice *vdev, VirtQueue *vq) VirtIOInputClass *vic = VIRTIO_INPUT_GET_CLASS(vdev); VirtIOInput *vinput = VIRTIO_INPUT(vdev); virtio_input_event event; - VirtQueueElement elem; + VirtQueueElement *elem; int len; - while (virtqueue_pop(vinput->sts, &elem)) { + for (;;) { + elem = virtqueue_pop(vinput->sts, sizeof(VirtQueueElement)); + if (!elem) { + break; + } + memset(&event, 0, sizeof(event)); - len = iov_to_buf(elem.out_sg, elem.out_num, + len = iov_to_buf(elem->out_sg, elem->out_num, 0, &event, sizeof(event)); if (vic->handle_status) { vic->handle_status(vinput, &event); } - virtqueue_push(vinput->sts, &elem, len); + virtqueue_push(vinput->sts, elem, len); + g_free(elem); } virtio_notify(vdev, vinput->sts); } -- cgit 1.4.1