Diff for /wikisrc/tutorials/how_to_enable_and_run_dtrace.mdwn between versions 1.18 and 1.28

version 1.18, 2017/04/08 21:38:18 version 1.28, 2020/03/30 15:40:27
Line 12  DTrace is a work-in-progress effort and  Line 12  DTrace is a work-in-progress effort and 
   
 ## Supported providers  ## Supported providers
   
 * SDT: Statically Defined Tracing  * DTrace: What to do when a script BEGINs, ENDs, ERRORs
 * FBT: Function Boundary Tracing  * FBT: Function Boundary Tracing
   * IO: Disk I/O
 * Lockstat: Kernel Lock Statistics  * Lockstat: Kernel Lock Statistics
   * Proc: Process and thread related events
 * Profile: Time based interrupt event source for Profiling  * Profile: Time based interrupt event source for Profiling
   * SDT: Statically Defined Tracing
 * Syscall: System Calls  * Syscall: System Calls
 * Syscall Linux (32bit & 64 bit): System calls via the Linux binary emulation layer  * Syscall Linux (32bit & 64 bit): System calls via the Linux binary emulation layer
   * VFS: Filesystem operations (confined to namecache events at time of writing - 8.99.22)
   
 ## TODO for netbsd-7  ## TODO for netbsd-7
   
Line 25  DTrace is a work-in-progress effort and  Line 29  DTrace is a work-in-progress effort and 
 * Determine whether the profile module works and list it here.  * Determine whether the profile module works and list it here.
 * Integrate [[riz|users/riz]]'s syscall provider patch.  * Integrate [[riz|users/riz]]'s syscall provider patch.
   
 ## TODO for netbsd-6  
   
 Need to identify changes to pull up to netbsd-6 and pull them up.  
 Candidates:  
   
 * Profile provider.  
   
 # How to use  # How to use
   
 ##  Building DTrace   ##  Building DTrace 
Line 51  Set the system to load the solaris and d Line 48  Set the system to load the solaris and d
   
 For example, add the following to `/etc/modules.conf` (the file may not exist already on a system):  For example, add the following to `/etc/modules.conf` (the file may not exist already on a system):
           
     solaris  - `solaris`
     dtrace  - `dtrace`
     dtrace_sdt  - `dtrace_fbt`
     dtrace_fbt  - `dtrace_lockstat`
     dtrace_lockstat  - `dtrace_profile`
     dtrace_profile  - `dtrace_sdt`
     dtrace_syscall  - `dtrace_syscall`
   - `dtrace_syscall_linux`
           
 A `dtrace` device node is created automatically in `/dev/dtrace` when the modules are loaded into place.  A `dtrace` device node is created automatically in `/dev/dtrace` when the modules are loaded into place.
           
Line 85  List the dtrace probes  Line 83  List the dtrace probes 
     29141       proc                                                     lwp_exit      29141       proc                                                     lwp_exit
   
   
 ##  Running hello world   ## Running hello world 
   
 Put the following into the file hello.d:  Put the following into the file hello.d:
           
Line 103  Run the hello world script:  Line 101  Run the hello world script: 
     dtrace: script './hello.d' matched 1 probe      dtrace: script './hello.d' matched 1 probe
     CPU     ID                    FUNCTION:NAME      CPU     ID                    FUNCTION:NAME
       0      1                           :BEGIN   Hello world        0      1                           :BEGIN   Hello world
       
   
 A more complex example that traces the execution of a sleep operation  The same script could be executed as a one liner on the shell, using
   
       dtrace -n 'BEGIN { trace("Hello world"); exit(0); }'
   
   ## A more complex example
   
   The following script traces the execution of a sleep operation
 in the kernel. Put it in sleep.d:  in the kernel. Put it in sleep.d:
           
     #pragma D option flowindent      #pragma D option flowindent
       
     fbt::syscall:entry      syscall::nanosleep:entry
     /execname == "sleep" && guard++ == 0/      /execname == "sleep" && guard++ == 0/
     {      {
             self->traceme = 1;              self->traceme = 1;
             printf("fd: %d", arg0);  
     }      }
       
     fbt::syscall:entry /self->traceme/ {}      fbt:::
           /self->traceme/
     fbt::syscall:return      {}
   
       syscall::nanosleep:return
     /self->traceme/      /self->traceme/
     {      {
             self->traceme = 0;              self->traceme = 0;
             exit(0);              exit(0);
     }      }
       
   
 Start the script running (dtrace -s sleep.d) and then execute a "sleep 2" in another shell.   Start the script running:
   
       dtrace -s sleep.d
   
   This will take a while as the script instruments every function in the
   kernel. When it's ready, it will print a message like "dtrace: script
   'sleep.d' matched 59268 probes".  Then execute a "sleep 2" in another
   shell.
   
   ## Tools included in base
   
   Starting with NetBSD-8, on builds where `MKDTRACE=yes` is set, scripts from
   [Brendan Gregg's DTrace toolkit](https://github.com/opendtrace/toolkit/) are installed in base as standard.
   
   At present, the following scripts are installed in `/usr/sbin`: 
   
   - `dtruss` - An implementation of the truss utility in DTrace which traces the system calls
   made by a process
   - `execsnoop` - snoop on execution of processes as they occur
   - `opensnoop` - snoop on openning of files as they occur
   - `procsystime` -  print process system call time details.
   
   ## Troubleshooting
   
   The Compact C Type Format (CTF) has a 2^15 limit on types which can overflow, this prevents DTrace from
   working correctly.
   
   Check the number of types using `ctfdump` e.g
       ctfdump -S /netbsd
   
   Note the line which states `total number of types`, the value should by less than 32768.
   
   If overflow is not an issue, `libdtrace(3)` can provide some insight into what is going on via an
   environment variable. Define `DTRACE_DEBUG` before tracing.
   
        env DTRACE_DEBUG= execsnoop
   

Removed from v.1.18  
changed lines
  Added in v.1.28


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