lttng-ust(3): reword and fix style of `LTTNG_UST_ALLOW_BLOCKING` variable

[lttng-ust.git] / doc / man / lttng-ust.3.txt

diff --git a/doc/man/lttng-ust.3.txt b/doc/man/lttng-ust.3.txt
index 832e79ef865bfdf270b9977f60c7db4a81e66ce5..5c9c9f5de2167addcb4427aaedf5a581c456b754 100644 (file)
--- 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 <<state-dump,LTTng-UST state dump>> section above) if
-    set to `1`.
+    If set, prevents `liblttng-ust` from performing a base address state
+    dump (see the <<state-dump,LTTng-UST state dump>> section above).
 
 
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