2.8, 2.9, 2.10: since 2.8, LTTng keeps lost sub-buffer count in overwrite mode

[lttng-docs.git] / 2.8 / lttng-docs-2.8.txt

diff --git a/2.8/lttng-docs-2.8.txt b/2.8/lttng-docs-2.8.txt
index 78952fc5b63e1ca28c43585c5b90c61f87bd62f0..80cdf9a97056b32f8016385a150844133906318a 100644 (file)
--- a/2.8/lttng-docs-2.8.txt
+++ b/2.8/lttng-docs-2.8.txt
@@ -7,6 +7,9 @@ v2.8, 24 July 2017
 include::../common/copyright.txt[]
 
 
+include::../common/warning-not-maintained.txt[]
+
+
 include::../common/welcome.txt[]
 
 
@@ -357,6 +360,8 @@ becomes inactive or in real-time.
 [[installing-lttng]]
 == Installation
 
+include::../common/warning-installation-outdated.txt[]
+
 **LTTng** is a set of software <<plumbing,components>> which interact to
 <<instrumenting,instrument>> the Linux kernel and user applications, and
 to <<controlling-tracing,control tracing>> (start and stop
@@ -1530,10 +1535,14 @@ as soon as a there's no space left for a new event record, whereas in
 discard mode, the tracer only discards the event record that doesn't
 fit.
 
-In discard mode, LTTng increments a count of lost event records when
-an event record is lost and saves this count to the trace. In
-overwrite mode, LTTng keeps no information when it overwrites a
-sub-buffer before consuming it.
+In discard mode, LTTng increments a count of lost event records when an
+event record is lost and saves this count to the trace. In overwrite
+mode, since LTTng 2.8, LTTng increments a count of lost sub-buffers when
+a sub-buffer is lost and saves this count to the trace. In this mode,
+the exact number of lost event records in those lost sub-buffers is not
+saved to the trace. Trace analyses can use the trace's saved discarded
+event record and sub-buffer counts to decide whether or not to perform
+the analyses even if trace data is known to be missing.
 
 There are a few ways to decrease your probability of losing event
 records.