X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=doc%2Fman%2Flttng-ust.3.txt;h=9fd3e8b8035f2a728e700007f03e475a06547f0d;hb=273554e4e1c9747afc2b0911fd0d124708720cea;hp=0864dbbfaa1ebb560fcf8cbb0f852ffaaffa5a22;hpb=ca98b1d723952df3ca1c44642a3d71065a7aca6e;p=lttng-ust.git diff --git a/doc/man/lttng-ust.3.txt b/doc/man/lttng-ust.3.txt index 0864dbbf..9fd3e8b8 100644 --- a/doc/man/lttng-ust.3.txt +++ b/doc/man/lttng-ust.3.txt @@ -738,6 +738,12 @@ without a following man:exec(3) family system call. The library application with the `LD_PRELOAD` environment variable (see man:ld.so(8)). +To use `liblttng-ust` with a daemon application which closes file +descriptors that were not opened by it, preload the `liblttng-ust-fd.so` +library before you start the application. Typical use cases include +daemons closing all file descriptors after man:fork(2), and buggy +applications doing ``double-closes''. + Context information ~~~~~~~~~~~~~~~~~~~ @@ -763,12 +769,16 @@ information about event filtering. reverse-lookup the source location that caused the event to be emitted. -+perf:thread:COUNTER+:: +`perf:thread:COUNTER`:: perf counter named 'COUNTER'. Use `lttng add-context --list` to list the available perf counters. + Only available on IA-32 and x86-64 architectures. +`perf:thread:raw:rN:NAME`:: + perf counter with raw ID 'N' and custom name 'NAME'. See + man:lttng-add-context(1) for more details. + `pthread_id`:: POSIX thread identifier. Can be used on architectures where `pthread_t` maps nicely to an `unsigned long` type. @@ -796,7 +806,9 @@ build IDs, and their debug link information are emitted as events by the tracer. The following LTTng-UST state dump events exist and must be enabled -to record application state dumps. +to record application state dumps. Note that, during the state dump +phase, LTTng-UST can also emit _shared library load/unload_ events +(see <> below). `lttng_ust_statedump:start`:: Emitted when the state dump begins. @@ -821,16 +833,26 @@ Fields: |Field name |Description |`baddr` -|Base address of loaded executable +|Base address of loaded executable. |`memsz` -|Size of loaded executable in memory +|Size of loaded executable in memory. |`path` -|Path to loaded executable file +|Path to loaded executable file. |`is_pic` -|Whether the executable is position-independent code +|Whether or not the executable is position-independent code. + +|`has_build_id` +|Whether or not the executable has a build ID. If this field is 1, you +can expect that an `lttng_ust_statedump:build_id` event record follows +this one (not necessarily immediately after). + +|`has_debug_link` +|Whether or not the executable has debug link information. If this field +is 1, you can expect that an `lttng_ust_statedump:debug_link` event +record follows this one (not necessarily immediately after). |=== `lttng_ust_statedump:build_id`:: @@ -846,10 +868,10 @@ Fields: |Field name |Description |`baddr` -|Base address of loaded library +|Base address of loaded library. |`build_id` -|Build ID +|Build ID. |=== `lttng_ust_statedump:debug_link`:: @@ -865,16 +887,137 @@ Fields: |Field name |Description |`baddr` -|Base address of loaded library +|Base address of loaded library. + +|`crc` +|Debug link file's CRC. + +|`filename` +|Debug link file name. +|=== + + +[[ust-lib]] +Shared library load/unload tracking +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The <> and the LTTng-UST helper library +to instrument the dynamic linker (see man:liblttng-ust-dl(3)) can emit +**shared library load/unload tracking** events. + +The following shared library load/unload tracking events exist and must +be enabled to track the loading and unloading of shared libraries: + +`lttng_ust_lib:load`:: + Emitted when a shared library (shared object) is loaded. ++ +Fields: ++ +[options="header"] +|=== +|Field name |Description + +|`baddr` +|Base address of loaded library. + +|`memsz` +|Size of loaded library in memory. + +|`path` +|Path to loaded library file. + +|`has_build_id` +|Whether or not the library has a build ID. If this field is 1, you +can expect that an `lttng_ust_lib:build_id` event record follows +this one (not necessarily immediately after). + +|`has_debug_link` +|Whether or not the library has debug link information. If this field +is 1, you can expect that an `lttng_ust_lib:debug_link` event +record follows this one (not necessarily immediately after). +|=== + +`lttng_ust_lib:unload`:: + Emitted when a shared library (shared object) is unloaded. ++ +Fields: ++ +[options="header"] +|=== +|Field name |Description + +|`baddr` +|Base address of unloaded library. +|=== + +`lttng_ust_lib:build_id`:: + Emitted when a build ID is found in a loaded shared library (shared + object). See + https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html[Debugging Information in Separate Files] + for more information about build IDs. ++ +Fields: ++ +[options="header"] +|=== +|Field name |Description + +|`baddr` +|Base address of loaded library. + +|`build_id` +|Build ID. +|=== + +`lttng_ust_lib:debug_link`:: + Emitted when debug link information is found in a loaded + shared library (shared object). See + https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html[Debugging Information in Separate Files] + for more information about debug links. ++ +Fields: ++ +[options="header"] +|=== +|Field name |Description + +|`baddr` +|Base address of loaded library. |`crc` -|Debug link file's CRC +|Debug link file's CRC. |`filename` -|Debug link file name +|Debug link file name. |=== +Detect if LTTng-UST is loaded +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +To detect if `liblttng-ust` is loaded from an application: + +. Define the `lttng_ust_loaded` weak symbol globally: ++ +------------------------------------------------------------------------ +int lttng_ust_loaded __attribute__((weak)); +------------------------------------------------------------------------ ++ +This weak symbol is set by the constructor of `liblttng-ust`. + +. Test `lttng_ust_loaded` where needed: ++ +------------------------------------------------------------------------ +/* ... */ + +if (lttng_ust_loaded) { + /* LTTng-UST is loaded */ +} else { + /* LTTng-UST is NOT loaded */ +} + +/* ... */ +------------------------------------------------------------------------ + + [[example]] EXAMPLE -------