X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=doc%2Fman%2Flttng-enable-channel.1.txt;h=bec0906428c5bfba6e9f91ab3e8f783cd96b472e;hp=e238830d3bc63aafb722741dcd79897e80fc7612;hb=db0f7697361017ef0d00b2faf322b131b138fca5;hpb=b4867b3be09b040aa8da32d0fa417ff1ec2a40f9 diff --git a/doc/man/lttng-enable-channel.1.txt b/doc/man/lttng-enable-channel.1.txt index e238830d3..bec090642 100644 --- a/doc/man/lttng-enable-channel.1.txt +++ b/doc/man/lttng-enable-channel.1.txt @@ -12,8 +12,8 @@ SYNOPSIS Create a Linux kernel channel: [verse] -*lttng* ['GENERAL OPTIONS'] *enable-channel* option:--kernel - [option:--discard | option:--overwrite] [option:--output=(`mmap` | `splice`)] +*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *enable-channel* option:--kernel + [option:--overwrite] [option:--output=(`mmap` | `splice`)] [option:--subbuf-size='SIZE'] [option:--num-subbuf='COUNT'] [option:--switch-timer='PERIODUS'] [option:--read-timer='PERIODUS'] [option:--tracefile-size='SIZE'] [option:--tracefile-count='COUNT'] @@ -22,17 +22,18 @@ Create a Linux kernel channel: Create a user space channel: [verse] -*lttng* ['GENERAL OPTIONS'] *enable-channel* option:--userspace - [option:--discard | option:--overwrite] [option:--buffers-pid] +*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *enable-channel* option:--userspace + [option:--overwrite] [option:--buffers-pid] [option:--subbuf-size='SIZE'] [option:--num-subbuf='COUNT'] [option:--switch-timer='PERIODUS'] [option:--read-timer='PERIODUS'] + [option:--blocking-timeout='TIMEOUTUS'] [option:--tracefile-size='SIZE'] [option:--tracefile-count='COUNT'] [option:--session='SESSION'] 'CHANNEL' Enable existing channel(s): [verse] -*lttng* ['GENERAL OPTIONS'] *enable-channel* (option:--userspace | option:--kernel) +*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *enable-channel* (option:--userspace | option:--kernel) [option:--session='SESSION'] 'CHANNEL'[,'CHANNEL']... @@ -42,7 +43,7 @@ The `lttng enable-channel` command can create a new channel, or enable one or more existing and disabled ones. A channel is the owner of sub-buffers holding recorded events. Event, -rules, when created using linklttng:lttng-enable-event(1), are always +rules, when created using man:lttng-enable-event(1), are always assigned to a channel. When creating a new channel, many parameters related to those sub-buffers can be fine-tuned. They are described in the subsections below. @@ -51,30 +52,21 @@ When 'CHANNEL' does not name an existing channel, a channel named 'CHANNEL' is created. Otherwise, the disabled channel named 'CHANNEL' is enabled. -Note that the linklttng:lttng-enable-event(1) command can automatically +Note that the man:lttng-enable-event(1) command can automatically create default channels when no channel exist. A channel is always contained in a tracing session -(see linklttng:lttng-create(1) for creating a tracing session). The +(see man:lttng-create(1) for creating a tracing session). The session in which a channel is created using `lttng enable-channel` can be specified using the option:--session option. If the option:--session option is omitted, the current tracing session is targeted. Existing enabled channels can be disabled using -linklttng:lttng-disable-channel(1). Channels of a given session can be -listed using linklttng:lttng-list(1). +man:lttng-disable-channel(1). Channels of a given session can be +listed using man:lttng-list(1). -As of this version of LTTng, it is not possible to: - -* Reconfigure a channel once it is created. -* Re-enable a disabled channel once its tracing session has been active - at least once. -* Create a channel once its tracing session has been active - at least once. -* Create a user space channel with a given buffering scheme - (option:--buffers-uid or option:--buffers-pid options) and create - a second user space channel with a different buffering scheme in the - same tracing session. +See the <> section below for a list of +limitations of this command to consider. Event loss modes @@ -209,10 +201,11 @@ in conjunction with the option:--tracefile-size option. For example, consider this command: ------------------------------------------------------ -lttng enable-channel --kernel --tracefile-size=4096 \ +[role="term"] +---- +$ lttng enable-channel --kernel --tracefile-size=4096 \ --tracefile-count=32 my-channel ------------------------------------------------------ +---- Here, for each stream, the maximum size of each trace file is 4 kiB and there can be a maximum of 32 different files. When there is @@ -236,7 +229,7 @@ option:-u, option:--userspace:: Target ~~~~~~ -option:-s, option:--session='SESSION':: +option:-s 'SESSION', option:--session='SESSION':: Create or enable channel in the tracing session named 'SESSION' instead of the current tracing session. @@ -260,8 +253,12 @@ option:--num-subbuf='COUNT':: + Default values: + -* `metadata` channel: 2 -* Everything else: 4 +* option:--userspace and option:--buffers-uid options: + {default_ust_uid_channel_subbuf_num} +* option:--userspace and option:--buffers-pid options: + {default_ust_pid_channel_subbuf_num} +* option:--kernel option: {default_kernel_channel_subbuf_num} +* `metadata` channel: {default_metadata_subbuf_num} option:--subbuf-size='SIZE':: Set the individual size of sub-buffers to 'SIZE' bytes. @@ -274,10 +271,12 @@ command shows the current system's page size: `getconf PAGE_SIZE`. + Default values: + -* option:--userspace and option:--buffers-uid options: `128k` -* option:--userspace and option:--buffers-pid options: `4k` -* option:--kernel option: `256k` -* `metadata` channel: `4k` +* option:--userspace and option:--buffers-uid options: + {default_ust_uid_channel_subbuf_size} +* option:--userspace and option:--buffers-pid options: + {default_ust_pid_channel_subbuf_size} +* option:--kernel option: {default_kernel_channel_subbuf_size} +* `metadata` channel: {default_metadata_subbuf_size} option:--output='TYPE':: Set channel's output type to 'TYPE'. @@ -314,7 +313,8 @@ Trace files ~~~~~~~~~~~ option:--tracefile-count='COUNT':: Limit the number of trace files created by this channel to - 'COUNT'. 0 means unlimited. Default: 0. + 'COUNT'. 0 means unlimited. Default: + {default_channel_tracefile_count}. + Use this option in conjunction with the option:--tracefile-size option. + @@ -325,7 +325,7 @@ the first trace file of the stream is cleared and used again. option:--tracefile-size='SIZE':: Set the maximum size of each trace file written by this channel within a stream to 'SIZE' bytes. 0 means unlimited. - Default: 0. + Default: {default_channel_tracefile_size}. + Note: traces generated with this option may inaccurately report discarded events as of CTF 1.8. @@ -339,23 +339,71 @@ option:--read-timer:: + Default values: + -* option:--userspace and option:--buffers-uid options: 0 -* option:--userspace and option:--buffers-pid options: 0 -* option:--kernel option: 200000 -* `metadata` channel: 0 +* option:--userspace and option:--buffers-uid options: + {default_ust_uid_channel_read_timer} +* option:--userspace and option:--buffers-pid options: + {default_ust_pid_channel_read_timer} +* option:--kernel option: {default_kernel_channel_read_timer} +* `metadata` channel: {default_metadata_read_timer} option:--switch-timer='PERIODUS':: Set the channel's switch timer's period to 'PERIODUS' µs. 0 means - a disabled switch timer. Default: 0. + a disabled switch timer. ++ +Default values: ++ +* option:--userspace and option:--buffers-uid options: + {default_ust_uid_channel_switch_timer} +* option:--userspace and option:--buffers-pid options: + {default_ust_pid_channel_switch_timer} +* option:--kernel option: {default_kernel_channel_switch_timer} +* `metadata` channel: {default_metadata_switch_timer} + +Timeouts +~~~~~~~~ +option:--blocking-timeout='TIMEOUTUS':: + Set the channel's blocking timeout value to 'TIMEOUTUS' µs + for applications executed with a set `LTTNG_UST_ALLOW_BLOCKING` + environment variable: ++ +-- +0 (default):: + Do not block. + +-1:: + Block forever until room is available in the sub-buffer to write the + event record. + +__n__, a positive value:: + Wait for at most __n__ µs when trying to write into a sub-buffer. +-- include::common-cmd-help-options.txt[] +[[limitations]] +LIMITATIONS +----------- +As of this version of LTTng, it is not possible to perform the following +actions with the `lttng enable-channel` command: + +* Reconfigure a channel once it is created. +* Re-enable a disabled channel once its tracing session has been active + at least once. +* Create a channel once its tracing session has been active + at least once. +* Create a user space channel with a given buffering scheme + (option:--buffers-uid or option:--buffers-pid options) and create + a second user space channel with a different buffering scheme in the + same tracing session. + + include::common-cmd-footer.txt[] SEE ALSO -------- -linklttng:lttng-disable-channel(1), -linklttng:lttng(1) +man:lttng-disable-channel(1), +man:lttng(1), +man:lttng-ust(3)