Message ID | 20170209084047.7897-1-famz@redhat.com |
---|---|
State | New |
Headers | show |
On Thu, Feb 9, 2017 at 12:40 AM, Fam Zheng <famz@redhat.com> wrote: > 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> > --- > hw/block/dataplane/virtio-blk.c | 4 ++-- > hw/block/virtio-blk.c | 12 ++++++++++-- > hw/scsi/virtio-scsi-dataplane.c | 14 +++++++------- > hw/scsi/virtio-scsi.c | 14 +++++++++++--- > hw/virtio/virtio.c | 15 +++++++++------ > include/hw/virtio/virtio-blk.h | 2 +- > include/hw/virtio/virtio-scsi.h | 6 +++--- > include/hw/virtio/virtio.h | 4 ++-- > 8 files changed, 45 insertions(+), 26 deletions(-) > > diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c > index d1f9f63..5556f0e 100644 > --- a/hw/block/dataplane/virtio-blk.c > +++ b/hw/block/dataplane/virtio-blk.c > @@ -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 */ > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c > index 702eda8..baaa195 100644 > --- a/hw/block/virtio-blk.c > +++ b/hw/block/virtio-blk.c > @@ -581,10 +581,11 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) > return 0; > } > > -void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) > +bool virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) > { > VirtIOBlockReq *req; > MultiReqBuffer mrb = {}; > + bool progress = false; > > blk_io_plug(s->blk); > > @@ -592,6 +593,7 @@ void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) > virtio_queue_set_notification(vq, 0); > > while ((req = virtio_blk_get_request(s, vq))) { > + progress = true; > if (virtio_blk_handle_request(req, &mrb)) { > virtqueue_detach_element(req->vq, &req->elem, 0); > virtio_blk_free_request(req); > @@ -607,6 +609,12 @@ void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) > } > > blk_io_unplug(s->blk); > + return progress; > +} > + > +static void virtio_blk_handle_output_do(VirtIOBlock *s, VirtQueue *vq) > +{ > + virtio_blk_handle_vq(s, vq); > } > > static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) > @@ -622,7 +630,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) > return; > } > } > - virtio_blk_handle_vq(s, vq); > + virtio_blk_handle_output_do(s, vq); > } > > static void virtio_blk_dma_restart_bh(void *opaque) > diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c > index 6b8d0f0..74c95e0 100644 > --- a/hw/scsi/virtio-scsi-dataplane.c > +++ b/hw/scsi/virtio-scsi-dataplane.c > @@ -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; > diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c > index ce19eff..b01030b 100644 > --- a/hw/scsi/virtio-scsi.c > +++ b/hw/scsi/virtio-scsi.c > @@ -436,13 +436,16 @@ static inline void virtio_scsi_release(VirtIOSCSI *s) > } > } > > -void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq) > +bool virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq) > { > VirtIOSCSIReq *req; > + bool progress = false; > > while ((req = virtio_scsi_pop_req(s, vq))) { > + progress = true; > virtio_scsi_handle_ctrl_req(s, req); > } > + return progress; > } > > static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) > @@ -591,10 +594,11 @@ static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req) > scsi_req_unref(sreq); > } > > -void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > +bool virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > { > VirtIOSCSIReq *req, *next; > int ret = 0; > + bool progress = false; > > QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs); > > @@ -602,6 +606,7 @@ void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > virtio_queue_set_notification(vq, 0); > > while ((req = virtio_scsi_pop_req(s, vq))) { > + progress = true; > ret = virtio_scsi_handle_cmd_req_prepare(s, req); > if (!ret) { > QTAILQ_INSERT_TAIL(&reqs, req, next); > @@ -624,6 +629,7 @@ void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > QTAILQ_FOREACH_SAFE(req, &reqs, next, next) { > virtio_scsi_handle_cmd_req_submit(s, req); > } > + return progress; > } > > static void virtio_scsi_handle_cmd(VirtIODevice *vdev, VirtQueue *vq) > @@ -752,11 +758,13 @@ out: > virtio_scsi_release(s); > } > > -void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq) > +bool virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq) > { > if (s->events_dropped) { > virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0); > + return true; > } > + return false; > } > > static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq) > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 6365706..2461c06 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -97,7 +97,7 @@ struct VirtQueue > > uint16_t vector; > VirtIOHandleOutput handle_output; > - VirtIOHandleOutput handle_aio_output; > + VirtIOHandleAIOOutput handle_aio_output; > VirtIODevice *vdev; > EventNotifier guest_notifier; > EventNotifier host_notifier; > @@ -1287,14 +1287,16 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align) > virtio_queue_update_rings(vdev, n); > } > > -static void virtio_queue_notify_aio_vq(VirtQueue *vq) > +static bool virtio_queue_notify_aio_vq(VirtQueue *vq) > { > if (vq->vring.desc && vq->handle_aio_output) { > VirtIODevice *vdev = vq->vdev; > > trace_virtio_queue_notify(vdev, vq - vdev->vq, vq); > - vq->handle_aio_output(vdev, vq); > + return vq->handle_aio_output(vdev, vq); > } > + > + return false; > } > > static void virtio_queue_notify_vq(VirtQueue *vq) > @@ -2125,16 +2127,17 @@ static bool virtio_queue_host_notifier_aio_poll(void *opaque) > { > EventNotifier *n = opaque; > VirtQueue *vq = container_of(n, VirtQueue, host_notifier); > + bool progress; > > if (virtio_queue_empty(vq)) { > return false; > } > > - virtio_queue_notify_aio_vq(vq); > + progress = virtio_queue_notify_aio_vq(vq); > > /* In case the handler function re-enabled notifications */ > virtio_queue_set_notification(vq, 0); > - return true; > + return progress; > } > > static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) > @@ -2146,7 +2149,7 @@ static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) > } > > void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, > - VirtIOHandleOutput handle_output) > + VirtIOHandleAIOOutput handle_output) > { > if (handle_output) { > vq->handle_aio_output = handle_output; > diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h > index 9734b4c..d3c8a6f 100644 > --- a/include/hw/virtio/virtio-blk.h > +++ b/include/hw/virtio/virtio-blk.h > @@ -80,6 +80,6 @@ typedef struct MultiReqBuffer { > bool is_write; > } MultiReqBuffer; > > -void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq); > +bool virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq); > > #endif > diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h > index 7375196..f536f77 100644 > --- a/include/hw/virtio/virtio-scsi.h > +++ b/include/hw/virtio/virtio-scsi.h > @@ -126,9 +126,9 @@ void virtio_scsi_common_realize(DeviceState *dev, Error **errp, > VirtIOHandleOutput cmd); > > void virtio_scsi_common_unrealize(DeviceState *dev, Error **errp); > -void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq); > -void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq); > -void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq); > +bool virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq); > +bool virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq); > +bool virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq); > void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req); > void virtio_scsi_free_req(VirtIOSCSIReq *req); > void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev, > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > index 525da24..0863a25 100644 > --- a/include/hw/virtio/virtio.h > +++ b/include/hw/virtio/virtio.h > @@ -154,6 +154,7 @@ void virtio_error(VirtIODevice *vdev, const char *fmt, ...) GCC_FMT_ATTR(2, 3); > void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name); > > typedef void (*VirtIOHandleOutput)(VirtIODevice *, VirtQueue *); > +typedef bool (*VirtIOHandleAIOOutput)(VirtIODevice *, VirtQueue *); > > VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size, > VirtIOHandleOutput handle_output); > @@ -284,8 +285,7 @@ bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev); > EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq); > void virtio_queue_host_notifier_read(EventNotifier *n); > void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, > - void (*fn)(VirtIODevice *, > - VirtQueue *)); > + VirtIOHandleAIOOutput handle_output); > VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector); > VirtQueue *virtio_vector_next_queue(VirtQueue *vq); > > -- > 2.9.3 >
On 09/02/2017 09:40, Fam Zheng wrote: > 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> Looks good. The alternative is to disable altogether the event queue handler unless events_dropped is true. Paolo > --- > hw/block/dataplane/virtio-blk.c | 4 ++-- > hw/block/virtio-blk.c | 12 ++++++++++-- > hw/scsi/virtio-scsi-dataplane.c | 14 +++++++------- > hw/scsi/virtio-scsi.c | 14 +++++++++++--- > hw/virtio/virtio.c | 15 +++++++++------ > include/hw/virtio/virtio-blk.h | 2 +- > include/hw/virtio/virtio-scsi.h | 6 +++--- > include/hw/virtio/virtio.h | 4 ++-- > 8 files changed, 45 insertions(+), 26 deletions(-) > > diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c > index d1f9f63..5556f0e 100644 > --- a/hw/block/dataplane/virtio-blk.c > +++ b/hw/block/dataplane/virtio-blk.c > @@ -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 */ > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c > index 702eda8..baaa195 100644 > --- a/hw/block/virtio-blk.c > +++ b/hw/block/virtio-blk.c > @@ -581,10 +581,11 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) > return 0; > } > > -void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) > +bool virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) > { > VirtIOBlockReq *req; > MultiReqBuffer mrb = {}; > + bool progress = false; > > blk_io_plug(s->blk); > > @@ -592,6 +593,7 @@ void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) > virtio_queue_set_notification(vq, 0); > > while ((req = virtio_blk_get_request(s, vq))) { > + progress = true; > if (virtio_blk_handle_request(req, &mrb)) { > virtqueue_detach_element(req->vq, &req->elem, 0); > virtio_blk_free_request(req); > @@ -607,6 +609,12 @@ void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) > } > > blk_io_unplug(s->blk); > + return progress; > +} > + > +static void virtio_blk_handle_output_do(VirtIOBlock *s, VirtQueue *vq) > +{ > + virtio_blk_handle_vq(s, vq); > } > > static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) > @@ -622,7 +630,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) > return; > } > } > - virtio_blk_handle_vq(s, vq); > + virtio_blk_handle_output_do(s, vq); > } > > static void virtio_blk_dma_restart_bh(void *opaque) > diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c > index 6b8d0f0..74c95e0 100644 > --- a/hw/scsi/virtio-scsi-dataplane.c > +++ b/hw/scsi/virtio-scsi-dataplane.c > @@ -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; > diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c > index ce19eff..b01030b 100644 > --- a/hw/scsi/virtio-scsi.c > +++ b/hw/scsi/virtio-scsi.c > @@ -436,13 +436,16 @@ static inline void virtio_scsi_release(VirtIOSCSI *s) > } > } > > -void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq) > +bool virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq) > { > VirtIOSCSIReq *req; > + bool progress = false; > > while ((req = virtio_scsi_pop_req(s, vq))) { > + progress = true; > virtio_scsi_handle_ctrl_req(s, req); > } > + return progress; > } > > static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) > @@ -591,10 +594,11 @@ static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req) > scsi_req_unref(sreq); > } > > -void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > +bool virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > { > VirtIOSCSIReq *req, *next; > int ret = 0; > + bool progress = false; > > QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs); > > @@ -602,6 +606,7 @@ void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > virtio_queue_set_notification(vq, 0); > > while ((req = virtio_scsi_pop_req(s, vq))) { > + progress = true; > ret = virtio_scsi_handle_cmd_req_prepare(s, req); > if (!ret) { > QTAILQ_INSERT_TAIL(&reqs, req, next); > @@ -624,6 +629,7 @@ void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) > QTAILQ_FOREACH_SAFE(req, &reqs, next, next) { > virtio_scsi_handle_cmd_req_submit(s, req); > } > + return progress; > } > > static void virtio_scsi_handle_cmd(VirtIODevice *vdev, VirtQueue *vq) > @@ -752,11 +758,13 @@ out: > virtio_scsi_release(s); > } > > -void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq) > +bool virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq) > { > if (s->events_dropped) { > virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0); > + return true; > } > + return false; > } > > static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq) > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 6365706..2461c06 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -97,7 +97,7 @@ struct VirtQueue > > uint16_t vector; > VirtIOHandleOutput handle_output; > - VirtIOHandleOutput handle_aio_output; > + VirtIOHandleAIOOutput handle_aio_output; > VirtIODevice *vdev; > EventNotifier guest_notifier; > EventNotifier host_notifier; > @@ -1287,14 +1287,16 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align) > virtio_queue_update_rings(vdev, n); > } > > -static void virtio_queue_notify_aio_vq(VirtQueue *vq) > +static bool virtio_queue_notify_aio_vq(VirtQueue *vq) > { > if (vq->vring.desc && vq->handle_aio_output) { > VirtIODevice *vdev = vq->vdev; > > trace_virtio_queue_notify(vdev, vq - vdev->vq, vq); > - vq->handle_aio_output(vdev, vq); > + return vq->handle_aio_output(vdev, vq); > } > + > + return false; > } > > static void virtio_queue_notify_vq(VirtQueue *vq) > @@ -2125,16 +2127,17 @@ static bool virtio_queue_host_notifier_aio_poll(void *opaque) > { > EventNotifier *n = opaque; > VirtQueue *vq = container_of(n, VirtQueue, host_notifier); > + bool progress; > > if (virtio_queue_empty(vq)) { > return false; > } > > - virtio_queue_notify_aio_vq(vq); > + progress = virtio_queue_notify_aio_vq(vq); > > /* In case the handler function re-enabled notifications */ > virtio_queue_set_notification(vq, 0); > - return true; > + return progress; > } > > static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) > @@ -2146,7 +2149,7 @@ static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) > } > > void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, > - VirtIOHandleOutput handle_output) > + VirtIOHandleAIOOutput handle_output) > { > if (handle_output) { > vq->handle_aio_output = handle_output; > diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h > index 9734b4c..d3c8a6f 100644 > --- a/include/hw/virtio/virtio-blk.h > +++ b/include/hw/virtio/virtio-blk.h > @@ -80,6 +80,6 @@ typedef struct MultiReqBuffer { > bool is_write; > } MultiReqBuffer; > > -void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq); > +bool virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq); > > #endif > diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h > index 7375196..f536f77 100644 > --- a/include/hw/virtio/virtio-scsi.h > +++ b/include/hw/virtio/virtio-scsi.h > @@ -126,9 +126,9 @@ void virtio_scsi_common_realize(DeviceState *dev, Error **errp, > VirtIOHandleOutput cmd); > > void virtio_scsi_common_unrealize(DeviceState *dev, Error **errp); > -void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq); > -void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq); > -void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq); > +bool virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq); > +bool virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq); > +bool virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq); > void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req); > void virtio_scsi_free_req(VirtIOSCSIReq *req); > void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev, > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > index 525da24..0863a25 100644 > --- a/include/hw/virtio/virtio.h > +++ b/include/hw/virtio/virtio.h > @@ -154,6 +154,7 @@ void virtio_error(VirtIODevice *vdev, const char *fmt, ...) GCC_FMT_ATTR(2, 3); > void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name); > > typedef void (*VirtIOHandleOutput)(VirtIODevice *, VirtQueue *); > +typedef bool (*VirtIOHandleAIOOutput)(VirtIODevice *, VirtQueue *); > > VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size, > VirtIOHandleOutput handle_output); > @@ -284,8 +285,7 @@ bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev); > EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq); > void virtio_queue_host_notifier_read(EventNotifier *n); > void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, > - void (*fn)(VirtIODevice *, > - VirtQueue *)); > + VirtIOHandleAIOOutput handle_output); > VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector); > VirtQueue *virtio_vector_next_queue(VirtQueue *vq); > >
On Thu, Feb 09, 2017 at 04:40:47PM +0800, Fam Zheng wrote: > 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> > --- > hw/block/dataplane/virtio-blk.c | 4 ++-- > hw/block/virtio-blk.c | 12 ++++++++++-- > hw/scsi/virtio-scsi-dataplane.c | 14 +++++++------- > hw/scsi/virtio-scsi.c | 14 +++++++++++--- > hw/virtio/virtio.c | 15 +++++++++------ > include/hw/virtio/virtio-blk.h | 2 +- > include/hw/virtio/virtio-scsi.h | 6 +++--- > include/hw/virtio/virtio.h | 4 ++-- > 8 files changed, 45 insertions(+), 26 deletions(-) Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index d1f9f63..5556f0e 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -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 */ diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 702eda8..baaa195 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -581,10 +581,11 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) return 0; } -void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) +bool virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) { VirtIOBlockReq *req; MultiReqBuffer mrb = {}; + bool progress = false; blk_io_plug(s->blk); @@ -592,6 +593,7 @@ void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) virtio_queue_set_notification(vq, 0); while ((req = virtio_blk_get_request(s, vq))) { + progress = true; if (virtio_blk_handle_request(req, &mrb)) { virtqueue_detach_element(req->vq, &req->elem, 0); virtio_blk_free_request(req); @@ -607,6 +609,12 @@ void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq) } blk_io_unplug(s->blk); + return progress; +} + +static void virtio_blk_handle_output_do(VirtIOBlock *s, VirtQueue *vq) +{ + virtio_blk_handle_vq(s, vq); } static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) @@ -622,7 +630,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq) return; } } - virtio_blk_handle_vq(s, vq); + virtio_blk_handle_output_do(s, vq); } static void virtio_blk_dma_restart_bh(void *opaque) diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c index 6b8d0f0..74c95e0 100644 --- a/hw/scsi/virtio-scsi-dataplane.c +++ b/hw/scsi/virtio-scsi-dataplane.c @@ -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; diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index ce19eff..b01030b 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -436,13 +436,16 @@ static inline void virtio_scsi_release(VirtIOSCSI *s) } } -void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq) +bool virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq) { VirtIOSCSIReq *req; + bool progress = false; while ((req = virtio_scsi_pop_req(s, vq))) { + progress = true; virtio_scsi_handle_ctrl_req(s, req); } + return progress; } static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq) @@ -591,10 +594,11 @@ static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req) scsi_req_unref(sreq); } -void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) +bool virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) { VirtIOSCSIReq *req, *next; int ret = 0; + bool progress = false; QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs); @@ -602,6 +606,7 @@ void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) virtio_queue_set_notification(vq, 0); while ((req = virtio_scsi_pop_req(s, vq))) { + progress = true; ret = virtio_scsi_handle_cmd_req_prepare(s, req); if (!ret) { QTAILQ_INSERT_TAIL(&reqs, req, next); @@ -624,6 +629,7 @@ void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq) QTAILQ_FOREACH_SAFE(req, &reqs, next, next) { virtio_scsi_handle_cmd_req_submit(s, req); } + return progress; } static void virtio_scsi_handle_cmd(VirtIODevice *vdev, VirtQueue *vq) @@ -752,11 +758,13 @@ out: virtio_scsi_release(s); } -void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq) +bool virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq) { if (s->events_dropped) { virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0); + return true; } + return false; } static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 6365706..2461c06 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -97,7 +97,7 @@ struct VirtQueue uint16_t vector; VirtIOHandleOutput handle_output; - VirtIOHandleOutput handle_aio_output; + VirtIOHandleAIOOutput handle_aio_output; VirtIODevice *vdev; EventNotifier guest_notifier; EventNotifier host_notifier; @@ -1287,14 +1287,16 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align) virtio_queue_update_rings(vdev, n); } -static void virtio_queue_notify_aio_vq(VirtQueue *vq) +static bool virtio_queue_notify_aio_vq(VirtQueue *vq) { if (vq->vring.desc && vq->handle_aio_output) { VirtIODevice *vdev = vq->vdev; trace_virtio_queue_notify(vdev, vq - vdev->vq, vq); - vq->handle_aio_output(vdev, vq); + return vq->handle_aio_output(vdev, vq); } + + return false; } static void virtio_queue_notify_vq(VirtQueue *vq) @@ -2125,16 +2127,17 @@ static bool virtio_queue_host_notifier_aio_poll(void *opaque) { EventNotifier *n = opaque; VirtQueue *vq = container_of(n, VirtQueue, host_notifier); + bool progress; if (virtio_queue_empty(vq)) { return false; } - virtio_queue_notify_aio_vq(vq); + progress = virtio_queue_notify_aio_vq(vq); /* In case the handler function re-enabled notifications */ virtio_queue_set_notification(vq, 0); - return true; + return progress; } static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) @@ -2146,7 +2149,7 @@ static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) } void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, - VirtIOHandleOutput handle_output) + VirtIOHandleAIOOutput handle_output) { if (handle_output) { vq->handle_aio_output = handle_output; diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h index 9734b4c..d3c8a6f 100644 --- a/include/hw/virtio/virtio-blk.h +++ b/include/hw/virtio/virtio-blk.h @@ -80,6 +80,6 @@ typedef struct MultiReqBuffer { bool is_write; } MultiReqBuffer; -void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq); +bool virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq); #endif diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h index 7375196..f536f77 100644 --- a/include/hw/virtio/virtio-scsi.h +++ b/include/hw/virtio/virtio-scsi.h @@ -126,9 +126,9 @@ void virtio_scsi_common_realize(DeviceState *dev, Error **errp, VirtIOHandleOutput cmd); void virtio_scsi_common_unrealize(DeviceState *dev, Error **errp); -void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq); -void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq); -void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq); +bool virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq); +bool virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq); +bool virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq); void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req); void virtio_scsi_free_req(VirtIOSCSIReq *req); void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev, diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 525da24..0863a25 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -154,6 +154,7 @@ void virtio_error(VirtIODevice *vdev, const char *fmt, ...) GCC_FMT_ATTR(2, 3); void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name); typedef void (*VirtIOHandleOutput)(VirtIODevice *, VirtQueue *); +typedef bool (*VirtIOHandleAIOOutput)(VirtIODevice *, VirtQueue *); VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size, VirtIOHandleOutput handle_output); @@ -284,8 +285,7 @@ bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev); EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq); void virtio_queue_host_notifier_read(EventNotifier *n); void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, - void (*fn)(VirtIODevice *, - VirtQueue *)); + VirtIOHandleAIOOutput handle_output); VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector); VirtQueue *virtio_vector_next_queue(VirtQueue *vq);
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> --- hw/block/dataplane/virtio-blk.c | 4 ++-- hw/block/virtio-blk.c | 12 ++++++++++-- hw/scsi/virtio-scsi-dataplane.c | 14 +++++++------- hw/scsi/virtio-scsi.c | 14 +++++++++++--- hw/virtio/virtio.c | 15 +++++++++------ include/hw/virtio/virtio-blk.h | 2 +- include/hw/virtio/virtio-scsi.h | 6 +++--- include/hw/virtio/virtio.h | 4 ++-- 8 files changed, 45 insertions(+), 26 deletions(-)