On 23.01.24 12:12, Fiona Ebner wrote:
[...]
I noticed poll_set_started() is not called, because
ctx->fdmon_ops->need_wait(ctx) was true, i.e. ctx->poll_disable_cnt was
positive (I'm using fdmon_poll). I then found this is because of the
notifier for the event vq, being attached with
virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, s->ctx);
in virtio_scsi_dataplane_start(). But in virtio_scsi_drained_end() it is
attached with virtio_queue_aio_attach_host_notifier() instead of the
_no_poll() variant. So that might be the actual issue here?
From a quick test, I cannot see the CPU-usage-spike issue with the
following either:
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 690aceec45..ba1ab8e410 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -1166,7 +1166,15 @@ static void virtio_scsi_drained_end(SCSIBus *bus)
for (uint32_t i = 0; i < total_queues; i++) {
VirtQueue *vq = virtio_get_queue(vdev, i);
- virtio_queue_aio_attach_host_notifier(vq, s->ctx);
+ if (!virtio_queue_get_notification(vq)) {
+ virtio_queue_set_notification(vq, true);
+ }
+ if (vq == VIRTIO_SCSI_COMMON(s)->event_vq) {
+ virtio_queue_aio_attach_host_notifier_no_poll(vq, s->ctx);
+ } else {
+ virtio_queue_aio_attach_host_notifier(vq, s->ctx);
+ }
+ virtio_queue_notify(vdev, i);
}
}
Perfect, so we agree on trying it that way. :)
Hanna
