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-rw-r--r--HOWTO/DTRACE.md343
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diff --git a/HOWTO/DTRACE.md b/HOWTO/DTRACE.md
index 90f4addefd..0c08b6cc3d 100644
--- a/HOWTO/DTRACE.md
+++ b/HOWTO/DTRACE.md
@@ -46,346 +46,11 @@ although it's considered experimental. The main development of the dtrace code
still happens outside of Ericsson, but there is no need to fetch a patched
version of the OTP source to get the basic funtionality.
-Implementation summary
-----------------------
+DTrace probe specifications
+---------------------------
-So far, most effort has been focused on the `efile_drv.c` code,
-which implements most file I/O on behalf of the Erlang virtual
-machine. This driver also presents a big challenge: its use of an I/O
-worker pool (enabled by using the `erl +A 8` flag, for example) makes
-it much more difficult to trace I/O activity because each of the
-following may be executed in a different Pthread:
-
-* I/O initiation (Erlang code)
-* I/O proxy process handling, e.g. read/write when file is not opened
- in `raw` mode, operations executed by the code & file server processes.
- (Erlang code)
-* `efile_drv` command setup (C code)
-* `efile_drv` command execution (C code)
-* `efile_drv` status return (C code)
-
-Example output from `lib/runtime_tools/examples/efile_drv.d` while executing
-`file:rename("old-name", "new-name")`:
-
- efile_drv enter tag={3,84} user tag some-user-tag | RENAME (12) | args: old-name new-name ,\
- 0 0 (port #Port<0.59>)
- async I/O worker tag={3,83} | RENAME (12) | efile_drv-int_entry
- async I/O worker tag={3,83} | RENAME (12) | efile_drv-int_return
- efile_drv return tag={3,83} user tag | RENAME (12) | errno 2
-
-... where the following key can help decipher the output:
-
-* `{3,83}` is the Erlang scheduler thread number (3) and operation
- counter number (83) assigned to this I/O operation. Together,
- these two numbers form a unique ID for the I/O operation.
-* `12` is the command number for the rename operation. See the
- definition for `FILE_RENAME` in the source code file `efile_drv.c`
- or the `BEGIN` section of the D script `lib/runtime_tools/examples/efile_drv.d`.
-* `old-name` and `new-name` are the two string arguments for the
- source and destination of the `rename(2)` system call.
- The two integer arguments are unused; the simple formatting code
- prints the arguments anyway, 0 and 0.
-* The worker pool code was called on behalf of Erlang port `#Port<0.59>`.
-* The system call failed with a POSIX errno value of 2: `ENOENT`,
- because the path `old-name` does not exist.
-* The `efile_drv-int_entry` and `efile_drv_int_return` probes are
- provided in case the user is
- interested in measuring only the latency of code executed by
- `efile_drv` asynchronous functions by I/O worker pool threads
- and the OS system call that they encapsulate.
-
-So, where does the `some-user-tag` string come from?
-
-At the moment, the user tag comes from code like the following:
-
- dyntrace:put_tag("some-user-tag"),
- file:rename("old-name", "new-name"),
-
-This method of tagging I/O at the Erlang level is subject to change.
-
-Example DTrace probe specification
-----------------------------------
-
- /**
- * Fired when a message is sent from one local process to another.
- *
- * NOTE: The 'size' parameter is in machine-dependent words and
- * that the actual size of any binary terms in the message
- * are not included.
- *
- * @param sender the PID (string form) of the sender
- * @param receiver the PID (string form) of the receiver
- * @param size the size of the message being delivered (words)
- * @param token_label for the sender's sequential trace token
- * @param token_previous count for the sender's sequential trace token
- * @param token_current count for the sender's sequential trace token
- */
- probe message__send(char *sender, char *receiver, uint32_t size,
- int token_label, int token_previous, int token_current);
-
- /**
- * Fired when a message is sent from a local process to a remote process.
- *
- * NOTE: The 'size' parameter is in machine-dependent words and
- * that the actual size of any binary terms in the message
- * are not included.
- *
- * @param sender the PID (string form) of the sender
- * @param node_name the Erlang node name (string form) of the receiver
- * @param receiver the PID/name (string form) of the receiver
- * @param size the size of the message being delivered (words)
- * @param token_label for the sender's sequential trace token
- * @param token_previous count for the sender's sequential trace token
- * @param token_current count for the sender's sequential trace token
- */
- probe message__send__remote(char *sender, char *node_name, char *receiver,
- uint32_t size,
- int token_label, int token_previous, int token_current);
-
- /**
- * Fired when a message is queued to a local process. This probe
- * will not fire if the sender's pid == receiver's pid.
- *
- * NOTE: The 'size' parameter is in machine-dependent words and
- * that the actual size of any binary terms in the message
- * are not included.
- *
- * @param receiver the PID (string form) of the receiver
- * @param size the size of the message being delivered (words)
- * @param queue_len length of the queue of the receiving process
- * @param token_label for the sender's sequential trace token
- * @param token_previous count for the sender's sequential trace token
- * @param token_current count for the sender's sequential trace token
- */
- probe message__queued(char *receiver, uint32_t size, uint32_t queue_len,
- int token_label, int token_previous, int token_current);
-
- /**
- * Fired when a message is 'receive'd by a local process and removed
- * from its mailbox.
- *
- * NOTE: The 'size' parameter is in machine-dependent words and
- * that the actual size of any binary terms in the message
- * are not included.
- *
- * @param receiver the PID (string form) of the receiver
- * @param size the size of the message being delivered (words)
- * @param queue_len length of the queue of the receiving process
- * @param token_label for the sender's sequential trace token
- * @param token_previous count for the sender's sequential trace token
- * @param token_current count for the sender's sequential trace token
- */
- probe message__receive(char *receiver, uint32_t size, uint32_t queue_len,
- int token_label, int token_previous, int token_current);
-
- /* ... */
-
- /* Async driver pool */
-
- /**
- * Show the post-add length of the async driver thread pool member's queue.
- *
- * NOTE: The port name is not available: additional lock(s) must
- * be acquired in order to get the port name safely in an SMP
- * environment. The same is true for the aio__pool_get probe.
- *
- * @param port the Port (string form)
- * @param new queue length
- */
- probe aio_pool__add(char *, int);
-
- /**
- * Show the post-get length of the async driver thread pool member's queue.
- *
- * @param port the Port (string form)
- * @param new queue length
- */
- probe aio_pool__get(char *, int);
-
- /* Probes for efile_drv.c */
-
- /**
- * Entry into the efile_drv.c file I/O driver
- *
- * For a list of command numbers used by this driver, see the section
- * "Guide to probe arguments" in ../../../README.md. That section
- * also contains explanation of the various integer and string
- * arguments that may be present when any particular probe fires.
- *
- * TODO: Adding the port string, args[10], is a pain. Making that
- * port string available to all the other efile_drv.c probes
- * will be more pain. Is the pain worth it? If yes, then
- * add them everywhere else and grit our teeth. If no, then
- * rip it out.
- *
- * @param thread-id number of the scheduler Pthread arg0
- * @param tag number: {thread-id, tag} uniquely names a driver operation
- * @param user-tag string arg2
- * @param command number arg3
- * @param string argument 1 arg4
- * @param string argument 2 arg5
- * @param integer argument 1 arg6
- * @param integer argument 2 arg7
- * @param integer argument 3 arg8
- * @param integer argument 4 arg9
- * @param port the port ID of the busy port args[10]
- */
- probe efile_drv__entry(int, int, char *, int, char *, char *,
- int64_t, int64_t, int64_t, int64_t, char *);
-
- /**
- * Entry into the driver's internal work function. Computation here
- * is performed by a async worker pool Pthread.
- *
- * @param thread-id number
- * @param tag number
- * @param command number
- */
- probe efile_drv__int_entry(int, int, int);
-
- /**
- * Return from the driver's internal work function.
- *
- * @param thread-id number
- * @param tag number
- * @param command number
- */
- probe efile_drv__int_return(int, int, int);
-
- /**
- * Return from the efile_drv.c file I/O driver
- *
- * @param thread-id number arg0
- * @param tag number arg1
- * @param user-tag string arg2
- * @param command number arg3
- * @param Success? 1 is success, 0 is failure arg4
- * @param If failure, the errno of the error. arg5
- */
- probe efile_drv__return(int, int, char *, int, int, int);
-
-Guide to efile_drv.c probe arguments
-------------------------------------
-
- /* Driver op code: used by efile_drv-entry arg3 */
- /* used by efile_drv-int_entry arg3 */
- /* used by efile_drv-int_return arg3 */
- /* used by efile_drv-return arg3 */
-
- #define FILE_OPEN 1 (probe arg3)
- probe arg6 = C driver dt_i1 = flags;
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_READ 2 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = flags;
- probe arg8 = C driver dt_i3 = size;
-
- #define FILE_LSEEK 3 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = offset;
- probe arg8 = C driver dt_i3 = origin;
-
- #define FILE_WRITE 4 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = flags;
- probe arg8 = C driver dt_i3 = size;
-
- #define FILE_FSTAT 5 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
-
- #define FILE_PWD 6 (probe arg3)
- none
-
- #define FILE_READDIR 7 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_CHDIR 8 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_FSYNC 9 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
-
- #define FILE_MKDIR 10 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_DELETE 11 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_RENAME 12 (probe arg3)
- probe arg4 = C driver dt_s1 = old_name;
- probe arg5 = C driver dt_s2 = new_name;
-
- #define FILE_RMDIR 13 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_TRUNCATE 14 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = flags;
-
- #define FILE_READ_FILE 15 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_WRITE_INFO 16 (probe arg3)
- probe arg6 = C driver dt_i1 = mode;
- probe arg7 = C driver dt_i2 = uid;
- probe arg8 = C driver dt_i3 = gid;
-
- #define FILE_LSTAT 19 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_READLINK 20 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_LINK 21 (probe arg3)
- probe arg4 = C driver dt_s1 = existing_path;
- probe arg5 = C driver dt_s2 = new_path;
-
- #define FILE_SYMLINK 22 (probe arg3)
- probe arg4 = C driver dt_s1 = existing_path;
- probe arg5 = C driver dt_s2 = new_path;
-
- #define FILE_CLOSE 23 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = flags;
-
- #define FILE_PWRITEV 24 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = flags;
- probe arg8 = C driver dt_i3 = size;
-
- #define FILE_PREADV 25 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = flags;
- probe arg8 = C driver dt_i3 = size;
-
- #define FILE_SETOPT 26 (probe arg3)
- probe arg6 = C driver dt_i1 = opt_name;
- probe arg7 = C driver dt_i2 = opt_specific_value;
-
- #define FILE_IPREAD 27 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = flags;
- probe arg8 = C driver dt_i3 = offsets[0];
- probe arg9 = C driver dt_i4 = size;
-
- #define FILE_ALTNAME 28 (probe arg3)
- probe arg4 = C driver dt_s1 = path;
-
- #define FILE_READ_LINE 29 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = flags;
- probe arg8 = C driver dt_i3 = read_offset;
- probe arg9 = C driver dt_i4 = read_ahead;
-
- #define FILE_FDATASYNC 30 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
-
- #define FILE_FADVISE 31 (probe arg3)
- probe arg6 = C driver dt_i1 = fd;
- probe arg7 = C driver dt_i2 = offset;
- probe arg8 = C driver dt_i3 = length;
- probe arg9 = C driver dt_i4 = advise_type;
+Probe specifications can be found in `erts/emulator/beam/erlang_dtrace.d`, and
+a few example scripts can be found under `lib/runtime_tools/examples/`.
[1]: http://www.erlang.org/euc/08/
[$ERL_TOP/HOWTO/SYSTEMTAP.md]: SYSTEMTAP.md