busstat -e device-inst | -h | -l
busstat [-a] [-n] [-w device-inst [,pic0=event,picn=event ]]... [-r device-inst]... [interval [count]]
busstat provides access to the bus-related performance counters in the system. These performance counters allow for the measurement of statistics like hardware clock cycles, bus statistics including DMA and cache coherency transactions on a multiprocessor system. Each bus device that supports these counters can be programmed to count a number of events from a specified list. Each device supports one or more Performance Instrumentation Counters (PIC) that are capable of counting events independently of each other.
Separate events can be selected for each PIC on each instance of these devices. busstat summarizes the counts over the last interval seconds, repeating forever. If a count is given, the statistics are repeated count times.
Only root users can program these counters. Non-root users have the option of reading the counters that have been programmed by a root user.
The default value for the interval argument is 1 second, and the default count is unlimited.
The devices that export these counters are highly platform-dependent and the data may be difficult to interpret without an in-depth understanding of the operation of the components that are being measured and of the system they reside in.
The following options are supported:
Display absolute counter values. The default is delta values.
Display the list of events that the specified device supports for each pic.
Specify device-inst as device (name) followed by an optional instance number. If an instance number is specified, the events for that instance are displayed. If no instance number is specified, the events for the first instance of the specified device are displayed.
Print a usage message.
List the devices in the system which support performance counters.
Do not display a title in the output. The default is to display titles.
Read and display all pic values for the specified device
Specify device-inst as device (name) followed by instance number, if specifying an instance number of a device whose counters are to be read and displayed. If all instances of this device are to be read, use device (name) without an instance number. All pic values will be sampled when using the –r option.
Program (write) the specified devices to count the specified events. Write access to the counters is restricted to root users only. Non-root users can use –r option.
Specify device-inst as device (name) followed by an optional instance number. If specifying an instance number of a device to program these events on. If all instances of this device are to be programmed the same, then use device without an instance number. Specify an event to be counted for a specified pic by providing a comma separated list of picn=event values.
The –e option displays all valid event names for each device. Any devices that are programmed will be sampled every interval seconds and repeated count times. It is recommended that the interval specified is small enough to ensure that counter wraparound will be detected. The rate at which counters wraparound varies from device to device. If a user is programming events using the –w option and busstat detects that another user has changed the events that are being counted, the tool will terminate as the programmed devices are now being controlled by another user. Only one user can be programming a device instance at any one time. Extra devices can be sampled using the –r option. Using multiple instances of the –w option on the same command line, with the same device-inst specifying a different list of events for the pics will give the effect of multiplexing for that device. busstat will switch between the list of events for that device every interval seconds. Event can be a string representing the event name, or even a number representing the bit pattern to be programmed into the Performance Control Register (PCR). This assumes explicit knowledge of the meaning of the control register bits for a device. The number can be specified in hexadecimal, decimal, or octal, using the usual conventions of strtol(3C).
The following exit values are returned:
An error occurred.
Another user is writing to the same devices.
In this example, ac0 refers to the Address Controller instance 0. The counters are programmed to count Memory Bank stalls on an Ultra Enterprise system at 10 second intervals with the values displayed in absolute form instead of deltas.
# busstat -a -w ac0,pic0=mem_bank0_stall,pic1=mem_bank1_stall 10 time dev event0 pic0 event1 pic1 10 ac0 mem_bank0_stall 1234 mem_bank1_stall 5678 20 ac0 mem_bank0_stall 5678 mem_bank1_stall 12345 30 ac0 mem_bank0_stall 12345 mem_bank1_stall 56789 ...
For a complete list of the supported events for a device, use the –e option.Example 2 Programming and monitoring the counters on all instances of the Address Controller
In this example, ac refers to all ac instances. This example programs all instances of the Address Controller counters to count_clock cycles and mem_bank0_rds at 2 second intervals, 100 times, displaying the values as deltas.
# busstat -w ac,pic0=clock_cycles,pic1=mem_bank0_rds 2 100 time dev event0 pic0 event1 pic1 2 ac0 clock_cycles 167242902 mem_bank0_rds 3144 2 ac1 clock_cycles 167254476 mem_bank0_rds 1392 4 ac0 clock_cycles 168025190 mem_bank0_rds 40302 4 ac1 clock_cycles 168024056 mem_bank0_rds 40580 ...Example 3 Monitoring the events being counted
This example monitors the events that are being counted on the sbus1 device, 100 times at 1 second intervals. It suggests that a root user has changed the events that sbus1 was counting to be dvma_tlb_misses and interrupts instead of pio_cycles.
% busstat -r sbus0 1 100 time dev event0 pic0 event1 pic1 1 sbus1 pio_cycles 2321 pio_cycles 2321 2 sbus1 pio_cycles 48 pio_cycles 48 3 sbus1 pio_cycles 49 pio_cycles 49 4 sbus1 pio_cycles 2281 pio_cycles 2281 5 sbus1 dvma_tlb_misses 0 interrupts 0 6 sbus1 dvma_tlb_misses 6 interrupts 2 7 sbus1 dvma_tlb_misses 8 interrupts 11 ...Example 4 Event Multiplexing
This example programs ac0 to alternate between counting (clock cycles, mem_bank0_rds) and (addr_pkts, data_pkts) at 2 second intervals while also monitoring what ac1 is counting :
It shows the expected output of the above busstat command. Another root user on the machine has changed the events that this user had programmed and busstat has detected this and terminates the command with a message.
# busstat -w ac0,pic0=clock_cycles,pic1=mem_bank0_rds \ -w ac0,pic0=addr_pkts,pic1=data_pkts \ -r ac1 2 time dev event0 pic0 event1 pic1 2 ac0 addr_pkts 12866 data_pkts 17015 2 ac1 rio_pkts 385 rio_pkts 385 4 ac0 clock_cycles 168018914 mem_bank0_rds 2865 4 ac1 rio_pkts 506 rio_pkts 506 6 ac0 addr_pkts 144236 data_pkts 149223 6 ac1 rio_pkts 522 rio_pkts 522 8 ac0 clock_cycles 168021245 mem_bank0_rds 2564 8 ac1 rio_pkts 387 rio_pkts 387 10 ac0 addr_pkts 144292 data_pkts 159645 10 ac1 rio_pkts 506 rio_pkts 506 12 ac0 clock_cycles 168020364 mem_bank0_rds 2665 12 ac1 rio_pkts 522 rio_pkts 522 busstat: events changed (possibly by another busstat). #
See attributes(5) for descriptions of the following attributes: