Patchwork [3/4] trace: document '-' syntax for disabling events

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Submitter Stefan Hajnoczi
Date Nov. 16, 2012, 1:19 p.m.
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Download mbox | patch
Permalink /patch/199594/
State New
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Stefan Hajnoczi - Nov. 16, 2012, 1:19 p.m.
Signed-off-by: Stefan Hajnoczi <>
 docs/tracing.txt | 4 ++++
 1 file changed, 4 insertions(+)


diff --git a/docs/tracing.txt b/docs/tracing.txt
index c541133..7901409 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