On Wed, Mar 21, 2018 at 11:21:24AM +0800, Peter Xu wrote:
> Add some trace points for IOTLB translation for vhost. After vhost-user
> is setup, the only IO path that QEMU will participate should be the
> IOMMU translation, so it'll be good we can track this with explicit
> timestamps when needed to see how long time we take to do the
> translation, and whether there's anything stuck inside. It might be
> useful for triaging vhost-user problems.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
Could you rebase pls?
> ---
> hw/virtio/trace-events | 1 +
> hw/virtio/vhost.c | 7 +++++++
> 2 files changed, 8 insertions(+)
>
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index 742ff0f90b..933eaab133 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -5,6 +5,7 @@ vhost_commit(bool started, bool changed) "Started: %d
> Changed: %d"
> vhost_region_add_section(const char *name, uint64_t gpa, uint64_t size,
> uint64_t host) "%s: 0x%"PRIx64"+0x%"PRIx64" @ 0x%"PRIx64
> vhost_region_add_section_abut(const char *name, uint64_t new_size) "%s:
> 0x%"PRIx64
> vhost_section(const char *name, int r) "%s:%d"
> +vhost_iotlb_miss(void *dev, int step) "%p step %d"
>
> # hw/virtio/virtio.c
> virtqueue_alloc_element(void *elem, size_t sz, unsigned in_num, unsigned
> out_num) "elem %p size %zd in_num %u out_num %u"
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index d8d0ef92e1..aa68f79510 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -839,12 +839,15 @@ int vhost_device_iotlb_miss(struct vhost_dev *dev,
> uint64_t iova, int write)
>
> rcu_read_lock();
>
> + trace_vhost_iotlb_miss(dev, 1);
> +
> iotlb = address_space_get_iotlb_entry(dev->vdev->dma_as,
> iova, write);
> if (iotlb.target_as != NULL) {
> ret = vhost_memory_region_lookup(dev, iotlb.translated_addr,
> &uaddr, &len);
> if (ret) {
> + trace_vhost_iotlb_miss(dev, 3);
> error_report("Fail to lookup the translated address "
> "%"PRIx64, iotlb.translated_addr);
> goto out;
> @@ -856,10 +859,14 @@ int vhost_device_iotlb_miss(struct vhost_dev *dev,
> uint64_t iova, int write)
> ret = vhost_backend_update_device_iotlb(dev, iova, uaddr,
> len, iotlb.perm);
> if (ret) {
> + trace_vhost_iotlb_miss(dev, 4);
> error_report("Fail to update device iotlb");
> goto out;
> }
> }
> +
> + trace_vhost_iotlb_miss(dev, 2);
> +
> out:
> rcu_read_unlock();
>
> --
> 2.14.3
