trace: document '-' syntax for disabling events

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2012-11-05 08:48:29 +01:00 · 2012-11-05 08:48:29 +01:00 · 8f5a0fb1f4
parent ddde8acc98
commit 8f5a0fb1f4
1 changed files with 4 additions and 0 deletions
--- 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