path: root/docs/tracing.txt
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1 files changed, 4 insertions, 0 deletions
diff --git a/docs/tracing.txt b/docs/tracing.txt
index c541133368..79014093db 100644
--- a/docs/tracing.txt
+++ b/docs/tracing.txt
@@ -139,6 +139,10 @@ having a common prefix in a batch. For example, virtio-blk trace events could
be enabled using:
trace-event virtio_blk_* on
+If a line in the "-trace events=<file>" file begins with a '-', the trace event
+will be disabled instead of enabled. This is useful when a wildcard was used
+to enable an entire family of events but one noisy event needs to be disabled.
== Trace backends ==
The "tracetool" script automates tedious trace event code generation and also