Re: [Qemu-devel] [PATCH] virtio-blk: trace vdev so devices can be distinguished

[Fam Zheng <famz@redhat.com>]

On Wed, 06/14 10:29, Stefan Hajnoczi wrote:
> It is hard to analyze trace logs with multiple virtio-blk devices
> because none of the trace events include the VirtIODevice *vdev.
> 
> This patch adds vdev so it's clear which device a request is associated
> with.
> 
> I considered using VirtIOBlock *s instead but VirtIODevice *vdev is more
> general and may be correlated with generic virtio trace events like
> virtio_set_status.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  hw/block/virtio-blk.c | 12 +++++++-----
>  hw/block/trace-events | 10 +++++-----
>  2 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 604d37d..c0bd247 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -50,7 +50,7 @@ static void virtio_blk_req_complete(VirtIOBlockReq *req, unsigned char status)
>      VirtIOBlock *s = req->dev;
>      VirtIODevice *vdev = VIRTIO_DEVICE(s);
>  
> -    trace_virtio_blk_req_complete(req, status);
> +    trace_virtio_blk_req_complete(vdev, req, status);
>  
>      stb_p(&req->in->status, status);
>      virtqueue_push(req->vq, &req->elem, req->in_len);
> @@ -88,12 +88,13 @@ static void virtio_blk_rw_complete(void *opaque, int ret)
>  {
>      VirtIOBlockReq *next = opaque;
>      VirtIOBlock *s = next->dev;
> +    VirtIODevice *vdev = VIRTIO_DEVICE(s);
>  
>      aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
>      while (next) {
>          VirtIOBlockReq *req = next;
>          next = req->mr_next;
> -        trace_virtio_blk_rw_complete(req, ret);
> +        trace_virtio_blk_rw_complete(vdev, req, ret);
>  
>          if (req->qiov.nalloc != -1) {
>              /* If nalloc is != 1 req->qiov is a local copy of the original
> @@ -355,7 +356,8 @@ static inline void submit_requests(BlockBackend *blk, MultiReqBuffer *mrb,
>              mrb->reqs[i - 1]->mr_next = mrb->reqs[i];
>          }
>  
> -        trace_virtio_blk_submit_multireq(mrb, start, num_reqs,
> +        trace_virtio_blk_submit_multireq(VIRTIO_DEVICE(mrb->reqs[start]->dev),

QOM casting is not strictly necessary because the parameter type is void *, but
it's clearer.

> +                                         mrb, start, num_reqs,
>                                           sector_num << BDRV_SECTOR_BITS,
>                                           qiov->size, is_write);
>          block_acct_merge_done(blk_get_stats(blk),
> @@ -526,11 +528,11 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb)
>  
>          if (is_write) {
>              qemu_iovec_init_external(&req->qiov, iov, out_num);
> -            trace_virtio_blk_handle_write(req, req->sector_num,
> +            trace_virtio_blk_handle_write(vdev, req, req->sector_num,
>                                            req->qiov.size / BDRV_SECTOR_SIZE);
>          } else {
>              qemu_iovec_init_external(&req->qiov, in_iov, in_num);
> -            trace_virtio_blk_handle_read(req, req->sector_num,
> +            trace_virtio_blk_handle_read(vdev, req, req->sector_num,
>                                           req->qiov.size / BDRV_SECTOR_SIZE);
>          }
>  
> diff --git a/hw/block/trace-events b/hw/block/trace-events
> index 65e83dc..c332c01 100644
> --- a/hw/block/trace-events
> +++ b/hw/block/trace-events
> @@ -1,11 +1,11 @@
>  # See docs/tracing.txt for syntax documentation.
>  
>  # hw/block/virtio-blk.c
> -virtio_blk_req_complete(void *req, int status) "req %p status %d"
> -virtio_blk_rw_complete(void *req, int ret) "req %p ret %d"
> -virtio_blk_handle_write(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
> -virtio_blk_handle_read(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
> -virtio_blk_submit_multireq(void *mrb, int start, int num_reqs, uint64_t offset, size_t size, bool is_write) "mrb %p start %d num_reqs %d offset %"PRIu64" size %zu is_write %d"
> +virtio_blk_req_complete(void *vdev, void *req, int status) "vdev %p req %p status %d"
> +virtio_blk_rw_complete(void *vdev, void *req, int ret) "vdev %p req %p ret %d"
> +virtio_blk_handle_write(void *vdev, void *req, uint64_t sector, size_t nsectors) "vdev %p req %p sector %"PRIu64" nsectors %zu"
> +virtio_blk_handle_read(void *vdev, void *req, uint64_t sector, size_t nsectors) "vdev %p req %p sector %"PRIu64" nsectors %zu"
> +virtio_blk_submit_multireq(void *vdev, void *mrb, int start, int num_reqs, uint64_t offset, size_t size, bool is_write) "vdev %p mrb %p start %d num_reqs %d offset %"PRIu64" size %zu is_write %d"
>  
>  # hw/block/hd-geometry.c
>  hd_geometry_lchs_guess(void *blk, int cyls, int heads, int secs) "blk %p LCHS %d %d %d"
> -- 
> 2.9.4
> 
> 

Reviewed-by: Fam Zheng <famz@redhat.com>