Re: [PATCH 1/2] vhost: basic tracepoints
On Tue, Apr 10, 2012 at 10:58:19AM +0800, Jason Wang wrote: To help for the performance optimizations and debugging, this patch tracepoints for vhost. Pay attention that the tracepoints are only for vhost, net code are not touched. Two kinds of activities were traced: virtio and vhost work. Signed-off-by: Jason Wang jasow...@redhat.com Thanks for looking into this. Some questions: Do we need to prefix traces with vhost_virtio_? How about a trace for enabling/disabling interrupts? Trace for a suppressed interrupt? I think we need a vq # not pointer. Also need some id for when there are many guests. Use the vhost thread name (includes owner pid)? It's pid? Both? Also, traces do add very small overhead when compiled but not enabled mainly due to increasing register pressure. Need to test to make sure perf is not hurt. Some traces are just for debugging so build them on debug kernel only? Further, there are many events some are rare some are common. I think we need some naming scheme so that really useful and low overhead stuff is easier to enable ignoring the rarely usefu;/higher overhead traces. --- drivers/vhost/trace.h | 153 + drivers/vhost/vhost.c | 17 + 2 files changed, 168 insertions(+), 2 deletions(-) create mode 100644 drivers/vhost/trace.h diff --git a/drivers/vhost/trace.h b/drivers/vhost/trace.h new file mode 100644 index 000..0423899 --- /dev/null +++ b/drivers/vhost/trace.h @@ -0,0 +1,153 @@ +#if !defined(_TRACE_VHOST_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_VHOST_H + +#include linux/tracepoint.h +#include vhost.h + +#undef TRACE_SYSTEM +#define TRACE_SYSTEM vhost + +/* + * Tracepoint for updating used flag. + */ +TRACE_EVENT(vhost_virtio_update_used_flags, + TP_PROTO(struct vhost_virtqueue *vq), + TP_ARGS(vq), + + TP_STRUCT__entry( + __field(struct vhost_virtqueue *, vq) + __field(u16, used_flags) + ), + + TP_fast_assign( + __entry-vq = vq; + __entry-used_flags = vq-used_flags; + ), + + TP_printk(vhost update used flag %x to vq %p notify %s, + __entry-used_flags, __entry-vq, + (__entry-used_flags VRING_USED_F_NO_NOTIFY) ? + disabled : enabled) +); + +/* + * Tracepoint for updating avail event. + */ +TRACE_EVENT(vhost_virtio_update_avail_event, + TP_PROTO(struct vhost_virtqueue *vq), + TP_ARGS(vq), + + TP_STRUCT__entry( + __field(struct vhost_virtqueue *, vq) + __field(u16, avail_idx) + ), + + TP_fast_assign( + __entry-vq = vq; + __entry-avail_idx = vq-avail_idx; + ), + + TP_printk(vhost update avail idx %u(%u) for vq %p, + __entry-avail_idx, __entry-avail_idx % + __entry-vq-num, __entry-vq) +); + +/* + * Tracepoint for processing descriptor. + */ +TRACE_EVENT(vhost_virtio_get_vq_desc, + TP_PROTO(struct vhost_virtqueue *vq, unsigned int index, + unsigned out, unsigned int in), + TP_ARGS(vq, index, out, in), + + TP_STRUCT__entry( + __field(struct vhost_virtqueue *, vq) + __field(unsigned int, head) + __field(unsigned int, out) + __field(unsigned int, in) + ), + + TP_fast_assign( + __entry-vq = vq; + __entry-head = index; + __entry-out = out; + __entry-in = in; + ), + + TP_printk(vhost get vq %p head %u out %u in %u, + __entry-vq, __entry-head, __entry-out, __entry-in) + +); + +/* + * Tracepoint for signal guest. + */ +TRACE_EVENT(vhost_virtio_signal, + TP_PROTO(struct vhost_virtqueue *vq), + TP_ARGS(vq), + + TP_STRUCT__entry( + __field(struct vhost_virtqueue *, vq) + ), + + TP_fast_assign( + __entry-vq = vq; + ), + + TP_printk(vhost signal vq %p, __entry-vq) +); + +DECLARE_EVENT_CLASS(vhost_work_template, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work), + + TP_STRUCT__entry( + __field(struct vhost_dev *, dev) + __field(struct vhost_work *, work) + __field(void *, function) + ), + + TP_fast_assign( + __entry-dev = dev; + __entry-work = work; + __entry-function = work-fn; + ), + + TP_printk(%pf for work %p dev %p, + __entry-function, __entry-work, __entry-dev) +); + +DEFINE_EVENT(vhost_work_template, vhost_work_queue_wakeup, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work)); + +DEFINE_EVENT(vhost_work_template, vhost_work_queue_coalesce, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work)); + +DEFINE_EVENT(vhost_work_template,
[PATCH 1/2] vhost: basic tracepoints
To help for the performance optimizations and debugging, this patch tracepoints for vhost. Pay attention that the tracepoints are only for vhost, net code are not touched. Two kinds of activities were traced: virtio and vhost work. Signed-off-by: Jason Wang jasow...@redhat.com --- drivers/vhost/trace.h | 153 + drivers/vhost/vhost.c | 17 + 2 files changed, 168 insertions(+), 2 deletions(-) create mode 100644 drivers/vhost/trace.h diff --git a/drivers/vhost/trace.h b/drivers/vhost/trace.h new file mode 100644 index 000..0423899 --- /dev/null +++ b/drivers/vhost/trace.h @@ -0,0 +1,153 @@ +#if !defined(_TRACE_VHOST_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_VHOST_H + +#include linux/tracepoint.h +#include vhost.h + +#undef TRACE_SYSTEM +#define TRACE_SYSTEM vhost + +/* + * Tracepoint for updating used flag. + */ +TRACE_EVENT(vhost_virtio_update_used_flags, + TP_PROTO(struct vhost_virtqueue *vq), + TP_ARGS(vq), + + TP_STRUCT__entry( + __field(struct vhost_virtqueue *, vq) + __field(u16, used_flags) + ), + + TP_fast_assign( + __entry-vq = vq; + __entry-used_flags = vq-used_flags; + ), + + TP_printk(vhost update used flag %x to vq %p notify %s, + __entry-used_flags, __entry-vq, + (__entry-used_flags VRING_USED_F_NO_NOTIFY) ? + disabled : enabled) +); + +/* + * Tracepoint for updating avail event. + */ +TRACE_EVENT(vhost_virtio_update_avail_event, + TP_PROTO(struct vhost_virtqueue *vq), + TP_ARGS(vq), + + TP_STRUCT__entry( + __field(struct vhost_virtqueue *, vq) + __field(u16, avail_idx) + ), + + TP_fast_assign( + __entry-vq = vq; + __entry-avail_idx = vq-avail_idx; + ), + + TP_printk(vhost update avail idx %u(%u) for vq %p, + __entry-avail_idx, __entry-avail_idx % + __entry-vq-num, __entry-vq) +); + +/* + * Tracepoint for processing descriptor. + */ +TRACE_EVENT(vhost_virtio_get_vq_desc, + TP_PROTO(struct vhost_virtqueue *vq, unsigned int index, +unsigned out, unsigned int in), + TP_ARGS(vq, index, out, in), + + TP_STRUCT__entry( + __field(struct vhost_virtqueue *, vq) + __field(unsigned int, head) + __field(unsigned int, out) + __field(unsigned int, in) + ), + + TP_fast_assign( + __entry-vq = vq; + __entry-head = index; + __entry-out = out; + __entry-in = in; + ), + + TP_printk(vhost get vq %p head %u out %u in %u, + __entry-vq, __entry-head, __entry-out, __entry-in) + +); + +/* + * Tracepoint for signal guest. + */ +TRACE_EVENT(vhost_virtio_signal, + TP_PROTO(struct vhost_virtqueue *vq), + TP_ARGS(vq), + + TP_STRUCT__entry( + __field(struct vhost_virtqueue *, vq) + ), + + TP_fast_assign( + __entry-vq = vq; + ), + + TP_printk(vhost signal vq %p, __entry-vq) +); + +DECLARE_EVENT_CLASS(vhost_work_template, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work), + + TP_STRUCT__entry( + __field(struct vhost_dev *, dev) + __field(struct vhost_work *, work) + __field(void *, function) + ), + + TP_fast_assign( + __entry-dev = dev; + __entry-work = work; + __entry-function = work-fn; + ), + + TP_printk(%pf for work %p dev %p, + __entry-function, __entry-work, __entry-dev) +); + +DEFINE_EVENT(vhost_work_template, vhost_work_queue_wakeup, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work)); + +DEFINE_EVENT(vhost_work_template, vhost_work_queue_coalesce, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work)); + +DEFINE_EVENT(vhost_work_template, vhost_poll_start, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work)); + +DEFINE_EVENT(vhost_work_template, vhost_poll_stop, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work)); + +DEFINE_EVENT(vhost_work_template, vhost_work_execute_start, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work)); + +DEFINE_EVENT(vhost_work_template, vhost_work_execute_end, + TP_PROTO(struct vhost_dev *dev, struct vhost_work *work), + TP_ARGS(dev, work)); + +#endif /* _TRACE_VHOST_H */ + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH ../../drivers/vhost +#undef TRACE_INCLUDE_FILE +#define TRACE_INCLUDE_FILE trace + +/* This part must be outside protection */ +#include trace/define_trace.h + diff --git
