ust update

git-svn-id: http://ltt.polymtl.ca/svn@3238 04897980-b3bd-0310-b5e0-8ef037075253

diff --git a/trunk/lttv/doc/developer/ust.txt b/trunk/lttv/doc/developer/ust.txt
index 03799389f6ea8fc83e0959e7bbdfe091b8093917..a379e553a93f0c5ccb1ce66507ab985d8b825b4e 100644 (file)
--- a/trunk/lttv/doc/developer/ust.txt
+++ b/trunk/lttv/doc/developer/ust.txt
@@ -31,3 +31,12 @@ The application may also spontaneously provide information to the pipe:
 In addition, the tracing control application should be notified when the
 application exits (to save the content of buffers if the application is
 crashing). Such notification may be obtained through utrace.
 In addition, the tracing control application should be notified when the
 application exits (to save the content of buffers if the application is
 crashing). Such notification may be obtained through utrace.

+
+This tracing scheme plans to use a direct function call to tracing into buffers
+mapped in user-space. This should be an order of magnitude faster than the
+current Dtrace implementation (c.f.
+https://ltt.polymtl.ca/tracingwiki/index.php/DTrace) which uses a breakpoint to
+perform both dynamic and static user-space tracing. Performance comparison of
+a function call vs the int3 approach is available at
+http://sourceware.org/ml/systemtap/2006-q3/msg00793.html (see "Conclusion").
+