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[PULL 17/27] virtio-blk: remove batch notification BH
From: |
Kevin Wolf |
Subject: |
[PULL 17/27] virtio-blk: remove batch notification BH |
Date: |
Tue, 31 Oct 2023 19:59:08 +0100 |
From: Stefan Hajnoczi <stefanha@redhat.com>
There is a batching mechanism for virtio-blk Used Buffer Notifications
that is no longer needed because the previous commit added batching to
virtio_notify_irqfd().
Note that this mechanism was rarely used in practice because it is only
enabled when EVENT_IDX is not negotiated by the driver. Modern drivers
enable EVENT_IDX.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230913200045.1024233-5-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
hw/block/dataplane/virtio-blk.c | 48 +--------------------------------
1 file changed, 1 insertion(+), 47 deletions(-)
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index da36fcfd0b..f83bb0f116 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -31,9 +31,6 @@ struct VirtIOBlockDataPlane {
VirtIOBlkConf *conf;
VirtIODevice *vdev;
- QEMUBH *bh; /* bh for guest notification */
- unsigned long *batch_notify_vqs;
- bool batch_notifications;
/* Note that these EventNotifiers are assigned by value. This is
* fine as long as you do not call event_notifier_cleanup on them
@@ -47,36 +44,7 @@ struct VirtIOBlockDataPlane {
/* Raise an interrupt to signal guest, if necessary */
void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq)
{
- if (s->batch_notifications) {
- set_bit(virtio_get_queue_index(vq), s->batch_notify_vqs);
- qemu_bh_schedule(s->bh);
- } else {
- virtio_notify_irqfd(s->vdev, vq);
- }
-}
-
-static void notify_guest_bh(void *opaque)
-{
- VirtIOBlockDataPlane *s = opaque;
- unsigned nvqs = s->conf->num_queues;
- unsigned long bitmap[BITS_TO_LONGS(nvqs)];
- unsigned j;
-
- memcpy(bitmap, s->batch_notify_vqs, sizeof(bitmap));
- memset(s->batch_notify_vqs, 0, sizeof(bitmap));
-
- for (j = 0; j < nvqs; j += BITS_PER_LONG) {
- unsigned long bits = bitmap[j / BITS_PER_LONG];
-
- while (bits != 0) {
- unsigned i = j + ctzl(bits);
- VirtQueue *vq = virtio_get_queue(s->vdev, i);
-
- virtio_notify_irqfd(s->vdev, vq);
-
- bits &= bits - 1; /* clear right-most bit */
- }
- }
+ virtio_notify_irqfd(s->vdev, vq);
}
/* Context: QEMU global mutex held */
@@ -126,9 +94,6 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev,
VirtIOBlkConf *conf,
} else {
s->ctx = qemu_get_aio_context();
}
- s->bh = aio_bh_new_guarded(s->ctx, notify_guest_bh, s,
- &DEVICE(vdev)->mem_reentrancy_guard);
- s->batch_notify_vqs = bitmap_new(conf->num_queues);
*dataplane = s;
@@ -146,8 +111,6 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
vblk = VIRTIO_BLK(s->vdev);
assert(!vblk->dataplane_started);
- g_free(s->batch_notify_vqs);
- qemu_bh_delete(s->bh);
if (s->iothread) {
object_unref(OBJECT(s->iothread));
}
@@ -173,12 +136,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
s->starting = true;
- if (!virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
- s->batch_notifications = true;
- } else {
- s->batch_notifications = false;
- }
-
/* Set up guest notifier (irq) */
r = k->set_guest_notifiers(qbus->parent, nvqs, true);
if (r != 0) {
@@ -370,9 +327,6 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
aio_context_release(s->ctx);
- qemu_bh_cancel(s->bh);
- notify_guest_bh(s); /* final chance to notify guest */
-
/* Clean up guest notifier (irq) */
k->set_guest_notifiers(qbus->parent, nvqs, false);
--
2.41.0
- [PULL 03/27] qemu-img: rebase: use backing files' BlockBackend for buffer alignment, (continued)
- [PULL 03/27] qemu-img: rebase: use backing files' BlockBackend for buffer alignment, Kevin Wolf, 2023/10/31
- [PULL 05/27] qemu-img: rebase: avoid unnecessary COW operations, Kevin Wolf, 2023/10/31
- [PULL 01/27] qemu-img: rebase: stop when reaching EOF of old backing file, Kevin Wolf, 2023/10/31
- [PULL 07/27] qemu-img: add compression option to rebase subcommand, Kevin Wolf, 2023/10/31
- [PULL 16/27] virtio: use defer_call() in virtio_irqfd_notify(), Kevin Wolf, 2023/10/31
- [PULL 19/27] block/mirror: set actively_synced even after the job is ready, Kevin Wolf, 2023/10/31
- [PULL 20/27] block/mirror: move dirty bitmap to filter, Kevin Wolf, 2023/10/31
- [PULL 21/27] block/mirror: determine copy_to_target only once, Kevin Wolf, 2023/10/31
- [PULL 15/27] util/defer-call: move defer_call() to util/, Kevin Wolf, 2023/10/31
- [PULL 06/27] iotests/{024, 271}: add testcases for qemu-img rebase, Kevin Wolf, 2023/10/31
- [PULL 17/27] virtio-blk: remove batch notification BH,
Kevin Wolf <=
- [PULL 09/27] block: Fix locking in media change monitor commands, Kevin Wolf, 2023/10/31
- [PULL 14/27] block: rename blk_io_plug_call() API to defer_call(), Kevin Wolf, 2023/10/31
- [PULL 11/27] blockjob: drop AioContext lock before calling bdrv_graph_wrlock(), Kevin Wolf, 2023/10/31
- [PULL 18/27] blockjob: introduce block-job-change QMP command, Kevin Wolf, 2023/10/31
- [PULL 12/27] block: avoid potential deadlock during bdrv_graph_wrlock() in bdrv_close(), Kevin Wolf, 2023/10/31
- [PULL 13/27] blockdev: mirror: avoid potential deadlock when using iothread, Kevin Wolf, 2023/10/31
- [PULL 10/27] iotests: Test media change with iothreads, Kevin Wolf, 2023/10/31
- [PULL 25/27] blockjob: query driver-specific info via a new 'query' driver method, Kevin Wolf, 2023/10/31
- [PULL 22/27] mirror: implement mirror_change method, Kevin Wolf, 2023/10/31
- [PULL 23/27] qapi/block-core: use JobType for BlockJobInfo's type, Kevin Wolf, 2023/10/31