virtio: Report real progress in VQ aio poll handler

In virtio_queue_host_notifier_aio_poll, not all "!virtio_queue_empty()"
cases are making true progress.

Currently the offending one is virtio-scsi event queue, whose handler
does nothing if no event is pending. As a result aio_poll() will spin on
the "non-empty" VQ and take 100% host CPU.

Fix this by reporting actual progress from virtio queue aio handlers.

Reported-by: Ed Swierk <eswierk@skyportsystems.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Tested-by: Ed Swierk <eswierk@skyportsystems.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Fam Zheng 2017-02-09 16:40:47 +08:00 committed by Michael S. Tsirkin
parent 4bb571d857
commit 0793169870
8 changed files with 45 additions and 26 deletions

View file

@ -147,7 +147,7 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
g_free(s);
}
static void virtio_blk_data_plane_handle_output(VirtIODevice *vdev,
static bool virtio_blk_data_plane_handle_output(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOBlock *s = (VirtIOBlock *)vdev;
@ -155,7 +155,7 @@ static void virtio_blk_data_plane_handle_output(VirtIODevice *vdev,
assert(s->dataplane);
assert(s->dataplane_started);
virtio_blk_handle_vq(s, vq);
return virtio_blk_handle_vq(s, vq);
}
/* Context: QEMU global mutex held */