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virtio: Report real progress in VQ aio poll handler

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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
Download patch file Download diff file Expand all files Collapse all files

14
hw/scsi/virtio-scsi-dataplane.c
View file

@ -49,35 +49,35 @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
}
}
static void virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
static bool virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOSCSI *s = (VirtIOSCSI *)vdev;
assert(s->ctx && s->dataplane_started);
virtio_scsi_handle_cmd_vq(s, vq);
return virtio_scsi_handle_cmd_vq(s, vq);
}
static void virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOSCSI *s = VIRTIO_SCSI(vdev);
assert(s->ctx && s->dataplane_started);
virtio_scsi_handle_ctrl_vq(s, vq);
return virtio_scsi_handle_ctrl_vq(s, vq);
}
static void virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
static bool virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOSCSI *s = VIRTIO_SCSI(vdev);
assert(s->ctx && s->dataplane_started);
virtio_scsi_handle_event_vq(s, vq);
return virtio_scsi_handle_event_vq(s, vq);
}
static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
void (*fn)(VirtIODevice *vdev, VirtQueue *vq))
VirtIOHandleAIOOutput fn)
{
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
int rc;