diff options
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/tracedump.txt | 58 | ||||
| -rw-r--r-- | Documentation/trace/tracelevel.txt | 42 |
2 files changed, 100 insertions, 0 deletions
diff --git a/Documentation/trace/tracedump.txt b/Documentation/trace/tracedump.txt new file mode 100644 index 00000000000..cba0decc3fc --- /dev/null +++ b/Documentation/trace/tracedump.txt | |||
| @@ -0,0 +1,58 @@ | |||
| 1 | Tracedump | ||
| 2 | |||
| 3 | Documentation written by Alon Farchy | ||
| 4 | |||
| 5 | 1. Overview | ||
| 6 | ============ | ||
| 7 | |||
| 8 | The tracedump module provides additional mechanisms to retrieve tracing data. | ||
| 9 | It can be used to retrieve traces after a kernel panic or while the system | ||
| 10 | is running in either binary format or plaintext. The dumped data is compressed | ||
| 11 | with zlib to conserve space. | ||
| 12 | |||
| 13 | 2. Configuration Options | ||
| 14 | ======================== | ||
| 15 | |||
| 16 | CONFIG_TRACEDUMP - enable the tracedump module. | ||
| 17 | CONFIG_TRACEDUMP_PANIC - dump to console on kernel panic | ||
| 18 | CONFIG_TRACEDUMP_PROCFS - add file /proc/tracedump for userspace access. | ||
| 19 | |||
| 20 | 3. Module Parameters | ||
| 21 | ==================== | ||
| 22 | |||
| 23 | format_ascii | ||
| 24 | |||
| 25 | If 1, data will dump in human-readable format, ordered by time. | ||
| 26 | If 0, data will be dumped as raw pages from the ring buffer, | ||
| 27 | ordered by CPU, followed by the saved cmdlines so that the | ||
| 28 | raw data can be decoded. Default: 0 | ||
| 29 | |||
| 30 | panic_size | ||
| 31 | |||
| 32 | Maximum amount of compressed data to dump during a kernel panic | ||
| 33 | in kilobytes. This only applies if format_ascii == 1. In this case, | ||
| 34 | tracedump will compress the data, check the size, and if it is too big | ||
| 35 | toss out some data, compress again, etc, until the size is below | ||
| 36 | panic_size. Default: 512KB | ||
| 37 | |||
| 38 | compress_level | ||
| 39 | |||
| 40 | Determines the compression level that zlib will use. Available levels | ||
| 41 | are 0-9, with 0 as no compression and 9 as maximum compression. | ||
| 42 | Default: 9. | ||
| 43 | |||
| 44 | 4. Usage | ||
| 45 | ======== | ||
| 46 | |||
| 47 | If configured with CONFIG_TRACEDUMP_PROCFS, the tracing data can be pulled | ||
| 48 | by reading from /proc/tracedump. For example: | ||
| 49 | |||
| 50 | # cat /proc/tracedump > my_tracedump | ||
| 51 | |||
| 52 | Tracedump will surround the dump with a magic word (TRACEDUMP). Between the | ||
| 53 | magic words is the compressed data, which can be decompressed with a standard | ||
| 54 | zlib implementation. After decompression, if format_ascii == 1, then the | ||
| 55 | output should be readable. | ||
| 56 | |||
| 57 | If format_ascii == 0, the output should be in binary form, delimited by | ||
| 58 | CPU_END. After the last CPU should be the saved cmdlines, delimited by |. | ||
diff --git a/Documentation/trace/tracelevel.txt b/Documentation/trace/tracelevel.txt new file mode 100644 index 00000000000..b282dd2b329 --- /dev/null +++ b/Documentation/trace/tracelevel.txt | |||
| @@ -0,0 +1,42 @@ | |||
| 1 | Tracelevel | ||
| 2 | |||
| 3 | Documentation by Alon Farchy | ||
| 4 | |||
| 5 | 1. Overview | ||
| 6 | =========== | ||
| 7 | |||
| 8 | Tracelevel allows subsystem authors to add trace priorities to | ||
| 9 | their tracing events. High priority traces will be enabled | ||
| 10 | automatically at boot time. | ||
| 11 | |||
| 12 | This module is configured with CONFIG_TRACELEVEL. | ||
| 13 | |||
| 14 | 2. Usage | ||
| 15 | ========= | ||
| 16 | |||
| 17 | To give an event a priority, use the function tracelevel_register | ||
| 18 | at any time. | ||
| 19 | |||
| 20 | tracelevel_register(my_event, level); | ||
| 21 | |||
| 22 | my_event corresponds directly to the event name as defined in the | ||
| 23 | event header file. Available levels are: | ||
| 24 | |||
| 25 | TRACELEVEL_ERR 3 | ||
| 26 | TRACELEVEL_WARN 2 | ||
| 27 | TRACELEVEL_INFO 1 | ||
| 28 | TRACELEVEL_DEBUG 0 | ||
| 29 | |||
| 30 | Any event registered at boot time as TRACELEVEL_ERR will be enabled | ||
| 31 | by default. The header also exposes the function tracelevel_set_level | ||
| 32 | to change the trace level at runtime. Any trace event registered with the | ||
| 33 | specified level or higher will be enabled with this call. | ||
| 34 | |||
| 35 | A userspace handle to tracelevel_set_level is available via the module | ||
| 36 | parameter 'level'. For example, | ||
| 37 | |||
| 38 | echo 1 > /sys/module/tracelevel/parameters/level | ||
| 39 | |||
| 40 | Is logically equivalent to: | ||
| 41 | |||
| 42 | tracelevel_set_level(TRACELEVEL_INFO); | ||
