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Solaris Dynamic Tracing Guide
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Document Information

Preface

1.  Introduction

2.  Types, Operators, and Expressions

3.  Variables

4.  D Program Structure

5.  Pointers and Arrays

6.  Strings

7.  Structs and Unions

8.  Type and Constant Definitions

9.  Aggregations

10.  Actions and Subroutines

11.  Buffers and Buffering

12.  Output Formatting

13.  Speculative Tracing

14.  dtrace(1M) Utility

15.  Scripting

16.  Options and Tunables

17.  dtrace Provider

18.  lockstat Provider

19.  profile Provider

20.  fbt Provider

21.  syscall Provider

22.  sdt Provider

Probes

Examples

Creating SDT Probes

Declaring Probes

Probe Arguments

Stability

23.  sysinfo Provider

24.  vminfo Provider

25.  proc Provider

26.  sched Provider

27.  io Provider

28.  mib Provider

29.  fpuinfo Provider

30.  pid Provider

31.  plockstat Provider

32.  fasttrap Provider

33.  User Process Tracing

34.  Statically Defined Tracing for User Applications

35.  Security

36.  Anonymous Tracing

37.  Postmortem Tracing

38.  Performance Considerations

39.  Stability

40.  Translators

41.  Versioning

Glossary

Index

Examples

The following example is a script to observe callout behavior on a per-second basis:

#pragma D option quiet

sdt:::callout-start
{
    @callouts[((callout_t *)arg0)->c_func] = count();
}

tick-1sec
{
    printa("%40a %10@d\n", @callouts);
    clear(@callouts);
}

Running this example reveals the frequent users of timeout(9F) in the system, as shown in the following output:

# dtrace -s ./callout.d
                                    FUNC      COUNT
                            TS`ts_update          1
              uhci`uhci_cmd_timeout_hdlr          3
                          genunix`setrun          5
                     genunix`schedpaging          5
                         ata`ghd_timeout         10
 uhci`uhci_handle_root_hub_status_change        309

                                    FUNC      COUNT
              ip`tcp_time_wait_collector          1
                            TS`ts_update          1
              uhci`uhci_cmd_timeout_hdlr          3
                     genunix`schedpaging          4
                          genunix`setrun          8
                         ata`ghd_timeout         10
 uhci`uhci_handle_root_hub_status_change        300

                                    FUNC      COUNT
              ip`tcp_time_wait_collector          0
                        iprb`mii_portmon          1
                            TS`ts_update          1
              uhci`uhci_cmd_timeout_hdlr          3
                     genunix`schedpaging          4
                          genunix`setrun          7
                         ata`ghd_timeout         10
 uhci`uhci_handle_root_hub_status_change        300

The timeout(9F) interface only produces a single timer expiration. Consumers of timeout() requiring interval timer functionality typically reinstall their timeout from their timeout() handler. The following example shows this behavior:

#pragma D option quiet

sdt:::callout-start
{
    self->callout = ((callout_t *)arg0)->c_func;
}

fbt::timeout:entry
/self->callout && arg2 <= 100/
{
    /*
     * In this case, we are most interested in interval timeout(9F)s that
     * are short.  We therefore do a linear quantization from 0 ticks to
     * 100 ticks.  The system clock's frequency — set by the variable
     * "hz" — defaults to 100, so 100 system clock ticks is one second. 
     */
    @callout[self->callout] = lquantize(arg2, 0, 100);
}

sdt:::callout-end
{
    self->callout = NULL;
}

END
{
    printa("%a\n%@d\n\n", @callout);
}

Running this script and waiting several seconds before typing Control-C results in output similar to the following example:

# dtrace -s ./interval.d
^C
genunix`schedpaging

           value  ------------- Distribution ------------- count    
              24 |                                         0        
              25 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 20       
              26 |                                         0        


ata`ghd_timeout

           value  ------------- Distribution ------------- count    
               9 |                                         0        
              10 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 51       
              11 |                                         0        


uhci`uhci_handle_root_hub_status_change

           value  ------------- Distribution ------------- count    
               0 |                                         0        
               1 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1515     
               2 |                                         0

The output shows that uhci_handle_root_hub_status_change() in the uhci(7D) driver represents the shortest interval timer on the system: it is called every system clock tick.

The interrupt-start probe can be used to understand interrupt activity. The following example shows how to quantize the time spent executing an interrupt handler by driver name:

interrupt-start
{
    self->ts = vtimestamp;
}

interrupt-complete
/self->ts/
{
    this->devi = (struct dev_info *)arg0;
    @[stringof(`devnamesp[this->devi->devi_major].dn_name),
        this->devi->devi_instance] = quantize(vtimestamp - self->ts);
}

Running this script results in output similar to the following example:

# dtrace -s ./intr.d
dtrace: script './intr.d' matched 2 probes
^C
 isp                                                       0
           value  ------------- Distribution ------------- count    
            8192 |                                         0        
           16384 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1        
           32768 |                                         0        

  pcf8584                                                   0
           value  ------------- Distribution ------------- count    
              64 |                                         0        
             128 |                                         2        
             256 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@         157      
             512 |@@@@@@                                   31       
            1024 |                                         3        
            2048 |                                         0        

  pcf8584                                                   1
           value  ------------- Distribution ------------- count    
            2048 |                                         0        
            4096 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@          154      
            8192 |@@@@@@@                                  37       
           16384 |                                         2        
           32768 |                                         0        

  qlc                                                       0
           value  ------------- Distribution ------------- count    
           16384 |                                         0        
           32768 |@@                                       9        
           65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@      126      
          131072 |@                                        5        
          262144 |                                         2        
          524288 |                                         0        

  hme                                                       0
           value  ------------- Distribution ------------- count    
            1024 |                                         0        
            2048 |                                         6        
            4096 |                                         2        
            8192 |@@@@                                     89       
           16384 |@@@@@@@@@@@@@                            262      
           32768 |@                                        37       
           65536 |@@@@@@@                                  139      
          131072 |@@@@@@@@                                 161      
          262144 |@@@                                      73       
          524288 |                                         4        
         1048576 |                                         0        
         2097152 |                                         1        
         4194304 |                                         0        

  ohci                                                      0
           value  ------------- Distribution ------------- count    
            8192 |                                         0        
           16384 |                                         3        
           32768 |                                         1        
           65536 |@@@                                      143      
          131072 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@     1368     
          262144 |                                         0