Task queues provide several useful SDT probes. All the probes described in this section have the following two arguments:
The task queue pointer returned by ddi_taskq_create()
The pointer to the taskq_ent_t structure. Use this pointer in your D script to extract the function and the argument.
You can use these probes to collect precise timing information about individual task queues and individual tasks being executed through them. For example, the following script prints the functions that were scheduled through task queues for every 10 seconds:
# !/usr/sbin/dtrace -qs sdt:genunix::taskq-enqueue { this->tq = (taskq_t *)arg0; this->tqe = (taskq_ent_t *) arg1; @[this->tq->tq_name, this->tq->tq_instance, this->tqe->tqent_func] = count(); } tick-10s { printa ("%s(%d): %a called %@d times\n", @); trunc(@); } |
On a particular machine, the above D script produced the following output:
callout_taskq(1): genunix`callout_execute called 51 times callout_taskq(0): genunix`callout_execute called 701 times kmem_taskq(0): genunix`kmem_update_timeout called 1 times kmem_taskq(0): genunix`kmem_hash_rescale called 4 times callout_taskq(1): genunix`callout_execute called 40 times USB_hid_81_pipehndl_tq_1(14): usba`hcdi_cb_thread called 256 times callout_taskq(0): genunix`callout_execute called 702 times kmem_taskq(0): genunix`kmem_update_timeout called 1 times kmem_taskq(0): genunix`kmem_hash_rescale called 4 times callout_taskq(1): genunix`callout_execute called 28 times USB_hid_81_pipehndl_tq_1(14): usba`hcdi_cb_thread called 228 times callout_taskq(0): genunix`callout_execute called 706 times callout_taskq(1): genunix`callout_execute called 24 times USB_hid_81_pipehndl_tq_1(14): usba`hcdi_cb_thread called 141 times callout_taskq(0): genunix`callout_execute called 708 times |