X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=doc%2Fman%2Flttng-ust.3.txt;h=5c9c9f5de2167addcb4427aaedf5a581c456b754;hb=3685664308de300b6612e706a2478121eb282c53;hp=832e79ef865bfdf270b9977f60c7db4a81e66ce5;hpb=636cf2a01500b8bef5a5959b4f1d3a9a7222b39a;p=lttng-ust.git diff --git a/doc/man/lttng-ust.3.txt b/doc/man/lttng-ust.3.txt index 832e79ef..5c9c9f5d 100644 --- a/doc/man/lttng-ust.3.txt +++ b/doc/man/lttng-ust.3.txt @@ -1292,29 +1292,23 @@ LTTng session and consumer daemons (part of the LTTng-tools project) are located in a specific directory under `$LTTNG_HOME` (or `$HOME` if `$LTTNG_HOME` is not set). -`LTTNG_UST_BLOCKING_RETRY_TIMEOUT`:: - Maximum duration (milliseconds) to retry event tracing when - there's no space left for the event record in the sub-buffer. +`LTTNG_UST_ALLOW_BLOCKING`:: + If set, allow the application to retry event tracing when there's + no space left for the event record in the sub-buffer, therefore + effectively blocking the application until space is made available + or the configured timeout is reached. + --- -`0` (default):: - Never block the application. - -Positive value:: - Block the application for the specified number of milliseconds. If - there's no space left after this duration, discard the event - record. - -Negative value:: - Block the application until there's space left for the event record. --- +To allow an application to block during tracing, you also need to +specify a blocking timeout when you create a channel with the +nloption:--blocking-timeout option of the man:lttng-enable-channel(1) +command. + This option can be useful in workloads generating very large trace data throughput, where blocking the application is an acceptable trade-off to prevent discarding event records. + -WARNING: Setting this environment variable to a non-zero value may -significantly affect application timings. +WARNING: Setting this environment variable may significantly +affect application timings. `LTTNG_UST_CLOCK_PLUGIN`:: Path to the shared object which acts as the clock override plugin. @@ -1323,7 +1317,7 @@ significantly affect application timings. https://github.com/lttng/lttng-ust/tree/master/doc/examples/clock-override[`examples/clock-override`]. `LTTNG_UST_DEBUG`:: - Activates `liblttng-ust`'s debug and error output if set to `1`. + If set, enable `liblttng-ust`'s debug and error output. `LTTNG_UST_GETCPU_PLUGIN`:: Path to the shared object which acts as the `getcpu()` override @@ -1341,28 +1335,9 @@ with time constraints on the process startup time. + Default: {lttng_ust_register_timeout}. -`LTTNG_UST_BLOCKING_RETRY_TIMEOUT`:: - Maximum time during which event tracing retry is attempted on buffer - full condition (millliseconds). Setting this environment to non-zero - value effectively blocks the application on buffer full condition. - Setting this environment variable to non-zero values may - significantly affect application timings. Setting this to a negative - value may block the application indefinitely if there is no consumer - emptying the ring buffer. The delay between retry attempts is the - minimum between the specified timeout value and 100ms. This option - can be useful in workloads generating very large trace data - throughput, where blocking the application is an acceptable - trade-off to not discard events. _Use with caution_. -+ -The value `0` means _do not retry_. The value `-1` means _retry forever_. -Value > `0` means a maximum timeout of the given value. -+ -Default: {lttng_ust_blocking_retry_timeout}. - `LTTNG_UST_WITHOUT_BADDR_STATEDUMP`:: - Prevents `liblttng-ust` from performing a base address state dump - (see the <> section above) if - set to `1`. + If set, prevents `liblttng-ust` from performing a base address state + dump (see the <> section above). include::common-footer.txt[]