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Annotation of wikisrc/tutorials/how_to_enable_and_run_dtrace.mdwn, revision 1.15

1.15    ! sevan       1: 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.
        !             2: 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/).
1.2       schmonz     3: 
1.5       wiki        4: # Current status
1.2       schmonz     5: 
1.5       wiki        6: ## Supported platforms
                      7: 
                      8: DTrace is a work-in-progress effort and it is for x86 systems and some arm boards.
                      9: 
                     10: * i386 and amd64
1.14      sevan      11: * earm* (evbarm and armv4 based ports (armv4 side requires further testing but system is built with CTF)
1.5       wiki       12: 
                     13: ## Supported providers
                     14: 
                     15: * SDT: Statically Defined Tracing
                     16: * FBT: Function Boundary Tracing
1.14      sevan      17: * Lockstat: Kernel Lock Statistics
                     18: * Profile: Time based interrupt event source for Profiling
                     19: * Syscall: System Calls
                     20: * Syscall Linux (32bit & 64 bit): System calls via the Linux binary emulation layer
1.2       schmonz    21: 
1.6       riastrad   22: ## TODO for netbsd-7
                     23: 
                     24: * Measure effect of `options KDTRACE_HOOKS` on system performance.
                     25: * Determine whether the profile module works and list it here.
1.7       riastrad   26: * Integrate [[riz|users/riz]]'s syscall provider patch.
1.6       riastrad   27: 
                     28: ## TODO for netbsd-6
                     29: 
                     30: Need to identify changes to pull up to netbsd-6 and pull them up.
                     31: Candidates:
                     32: 
                     33: * Profile provider.
                     34: 
1.5       wiki       35: # How to use
                     36: 
1.2       schmonz    37: ##  Building DTrace 
                     38: 
                     39: You need the following options in your kernel: 
                     40:     
1.10      wiz        41:     options         KDTRACE_HOOKS   # kernel DTrace hooks
1.2       schmonz    42:     options         MODULAR
                     43: 
1.14      sevan      44: Optionally:
                     45:     options         INSECURE   # permit modules to loaded from user space once system has gone multiuser and securelevel has been raised.
1.2       schmonz    46: 
1.14      sevan      47: 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`
1.2       schmonz    48: 
1.14      sevan      49: 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/`
1.2       schmonz    50:     
1.14      sevan      51:     solaris
                     52:     dtrace
                     53:     dtrace_sdt
                     54:     dtrace_fbt
                     55:     dtrace_lockstat
                     56:     dtrace_profile
                     57:     dtrace_syscall
1.2       schmonz    58:     
1.14      sevan      59: A `dtrace` device node is created automatically in `/dev/dtrace` when the modules are loaded into place.
1.2       schmonz    60:     
                     61: List the dtrace probes 
                     62:     
                     63:     dtrace -l
                     64:     
                     65:        ID   PROVIDER            MODULE                          FUNCTION NAME
                     66:         1     dtrace                                                     BEGIN
                     67:         2     dtrace                                                     END
                     68:         3     dtrace                                                     ERROR
                     69:         4        fbt            netbsd             AcpiAcquireGlobalLock entry
                     70:         5        fbt            netbsd             AcpiAcquireGlobalLock return
                     71:         6        fbt            netbsd             AcpiAllocateRootTable entry
                     72:         7        fbt            netbsd                    AcpiAttachData entry
                     73:         . 
                     74:         .
                     75:     29129        fbt           solaris                   zfs_vop_getattr entry 
                     76:     29130        fbt           solaris                   zfs_vop_getattr return
                     77:     29131       proc                                                     create
                     78:     29132       proc                                                     exec 
                     79:         .
                     80:         .
                     81:     29140       proc                                                     lwp_start
                     82:     29141       proc                                                     lwp_exit
                     83: 
                     84: 
1.14      sevan      85: ##  Running hello world 
1.2       schmonz    86: 
1.9       wiz        87: Put the following into the file hello.d:
1.2       schmonz    88:     
                     89:     BEGIN
                     90:     {
                     91:         trace("Hello world");
                     92:         exit(0);
                     93:     }
                     94:     
                     95: 
                     96: Run the hello world script: 
                     97:     
                     98:     dtrace -s hello.d
                     99:     
                    100:     dtrace: script './hello.d' matched 1 probe
                    101:     CPU     ID                    FUNCTION:NAME
                    102:       0      1                           :BEGIN   Hello world
                    103:     
                    104: 
1.9       wiz       105: A more complex example that traces the execution of a sleep operation
                    106: in the kernel. Put it in sleep.d:
1.2       schmonz   107:     
                    108:     #pragma D option flowindent
                    109:     
                    110:     fbt::syscall:entry
                    111:     /execname == "sleep" && guard++ == 0/
                    112:     {
                    113:             self->traceme = 1;
                    114:             printf("fd: %d", arg0);
                    115:     }
                    116:     
1.9       wiz       117:     fbt::syscall:entry /self->traceme/ {}
1.2       schmonz   118:     
                    119:     fbt::syscall:return
                    120:     /self->traceme/
                    121:     {
                    122:             self->traceme = 0;
                    123:             exit(0);
                    124:     }
                    125:     
                    126: 
1.9       wiz       127: Start the script running (dtrace -s sleep.d) and then execute a "sleep 2" in another shell.