Diff for /wikisrc/tutorials/how_to_enable_and_run_dtrace.mdwn between versions 1.3 and 1.26

version 1.3, 2013/07/03 23:14:31 version 1.26, 2018/07/22 17:18:06
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 DTrace is a Dynamic Tracing framework developed by Sun and ported to NetBSD. It enables extensive instrumentation of the kernel and user space. See the [DTrace Community Page](http://hub.opensolaris.org/bin/view/Community+Group+dtrace/WebHome) for more information. Also see [DTrace Introduction](http://wikis.sun.com/display/DTrace/Introduction).   DTrace is a Dynamic Tracing framework developed by Sun and ported to NetBSD. It enables extensive instrumentation of the kernel and user space. See the [DTrace Community Page](http://dtrace.org) for more information.
   Also see [DTrace Introduction](http://dtrace.org/guide/preface.html), Brendan Gregg's [DTrace one liners](http://www.brendangregg.com/DTrace/dtrace_oneliners.txt) and his notes for [DTrace on FreeBSD](https://wiki.freebsd.org/DTrace/).
   # Current status
 DTrace is a work-in-progress effort and it is for x86 systems only currently (there is some arm support but it is completely untested). Two providers are available; the Statically Defined Tracing (SDT) provider and the Function Boundary Tracer (FBT) provider.   ## Supported platforms
 You can currently run a hello world DScript.   DTrace is a work-in-progress effort and it is for x86 systems and some arm boards.
   * i386 and amd64
   * earm* (evbarm and armv4 based ports)
   ## Supported providers
   * DTrace: What to do when a script BEGINs, ENDs, ERRORs
   * FBT: Function Boundary Tracing
   * IO: Disk I/O
   * Lockstat: Kernel Lock Statistics
   * Proc: Process and thread related events
   * Profile: Time based interrupt event source for Profiling
   * SDT: Statically Defined Tracing
   * Syscall: System Calls
   * 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
   * Measure effect of `options KDTRACE_HOOKS` on system performance.
   * Determine whether the profile module works and list it here.
   * Integrate [[riz|users/riz]]'s syscall provider patch.
   # How to use
 ##  Building DTrace   ##  Building DTrace 
 You need the following options in your kernel:   You need the following options in your kernel: 
     options         INSECURE      options         KDTRACE_HOOKS   # kernel DTrace hooks
     options         KDTRACE_HOOKS   # DTrace support  
     options         MODULAR      options         MODULAR
 You also need to build distribution with the options MKMODULAR=yes and MKDTRACE=yes.   Optionally:
 ##  Running hello world       options         INSECURE   # permit modules to loaded from user space once system has gone multiuser and securelevel has been raised.
 Load the solaris and dtrace modules, and the SDT (Statically Defined Tracing) and FBT (Function Boundary Tracing) modules:   A Distribution needs to be built with the options `MKDTRACE=yes` and `MKCTF=yes`, this is taken care of automatically and doesn't need to be specified manually. The list of platforms it is applied to automatically is set in `src/share/mk/bsd.own.mk`
     modload solaris  Set the system to load the solaris and dtrace related modules in `/etc/modules.conf`, for a list of available modules, see `/stand/$MACHINE/$VERSION/modules/`
     modload dtrace  
     modload sdt  
     modload fbt  
 Make the dtrace device node:   For example, add the following to `/etc/modules.conf` (the file may not exist already on a system):
     mkdir /dev/dtrace  - `solaris`
     mknod /dev/dtrace/dtrace c dtrace 0  - `dtrace`
   - `dtrace_fbt`
   - `dtrace_lockstat`
   - `dtrace_profile`
   - `dtrace_sdt`
   - `dtrace_syscall`
   - `dtrace_syscall_linux`
   A `dtrace` device node is created automatically in `/dev/dtrace` when the modules are loaded into place.
 List the dtrace probes   List the dtrace probes 
     dtrace -l      dtrace -l
Line 54  List the dtrace probes  Line 81  List the dtrace probes 
         .          .
     29140       proc                                                     lwp_start      29140       proc                                                     lwp_start
     29141       proc                                                     lwp_exit      29141       proc                                                     lwp_exit
   ## Running hello world 
 Put the following into the file hello.d   Put the following into the file hello.d:
     BEGIN      BEGIN
     {      {
Line 77  Run the hello world script:  Line 103  Run the hello world script: 
       0      1                           :BEGIN   Hello world        0      1                           :BEGIN   Hello world
 A more complex example that traces the execution of a sleep operation in the kernel:   ## A more complex example
   The following script traces the execution of a sleep operation
   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:::      fbt:::
     /self->traceme/      /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 <scriptname.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
   ## 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.

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