This patch adds LTTng Userspace Tracer (UST) backend support. The UST
system requires no kernel support but libust and liburcu must be
installed.
$ ./configure --trace-backend ust
$ make
Start the UST daemon:
$ ustd
List available tracepoints and enable some:
$ ustctl --list-markers $(pgrep qemu)
[...]
{PID: 5458, channel/marker: ust/paio_submit, state: 0, fmt: acb %p
opaque %p sector_num %lu nb_sectors %lu type %lu 0x4b32ba}
$ ustctl --enable-marker ust/paio_submit $(pgrep qemu)
Run the trace:
$ ustctl --create-trace $(pgrep qemu)
$ ustctl --start-trace $(pgrep qemu)
[...]
$ ustctl --stop-trace $(pgrep qemu)
$ ustctl --destroy-trace $(pgrep qemu)
Trace results can be viewed using lttv-gui.
More information about UST:
http://lttng.org/ust
Signed-off-by: Stefan Hajnoczi stefa...@linux.vnet.ibm.com
---
I wrote this as part of trying out UST. Although UST is promising, the
usability is poor at the moment.
The dependencies include the lttv trace viewer which I had to build from source
(and it required a makefile tweak to build). Luckily libust, liburcu, and
ust-bin are packaged on my distro.
Error messages are periodically printed by the UST code when running QEMU. I
haven't investigated but this is may be due to signals interrupting UST's
thread in poll().
Finally, the UST header files include some userspace ported kernel
infrastructure and pollute the namespace. I had to add some #undefs to get
QEMU to build after including UST headers.
I don't see LTTng UST as a default option at the moment. Hopefully this will
change in the future.
configure |5 +++-
tracetool | 77 +++-
2 files changed, 79 insertions(+), 3 deletions(-)
diff --git a/configure b/configure
index d599879..307dbcb 100755
--- a/configure
+++ b/configure
@@ -829,7 +829,7 @@ echo --enable-docsenable documentation build
echo --disable-docs disable documentation build
echo --disable-vhost-net disable vhost-net acceleration support
echo --enable-vhost-net enable vhost-net acceleration support
-echo --trace-backend=BTrace backend nop simple
+echo --trace-backend=BTrace backend nop simple ust
echo
echo NOTE: The object files are built at the place where configure is
launched
exit 1
@@ -2302,6 +2302,9 @@ bsd)
esac
echo TRACE_BACKEND=$trace_backend $config_host_mak
+if test $trace_backend = ust; then
+ LIBS=-lust $LIBS
+fi
tools=
if test `expr $target_list : .*softmmu.*` != 0 ; then
diff --git a/tracetool b/tracetool
index bcd163e..72beb20 100755
--- a/tracetool
+++ b/tracetool
@@ -3,12 +3,13 @@
usage()
{
cat 2 EOF
-usage: $0 [--nop | --simple] [-h | -c | --py]
+usage: $0 [--nop | --simple | --ust] [-h | -c | --py]
Generate tracing code for a file on stdin.
Backends:
--nop Tracing disabled
--simple Simple built-in backend
+ --ust LTTng User Space Tracing backend
Output formats:
-hGenerate .h file
@@ -220,6 +221,78 @@ linetopy_end_simple()
echo }
}
+linetoh_begin_ust()
+{
+echo #include ust/tracepoint.h
+}
+
+linetoh_ust()
+{
+local name args argnames
+name=$(get_name $1)
+args=$(get_args $1)
+argnames=$(get_argnames $1)
+
+cat EOF
+DECLARE_TRACE(ust_$name, TPPROTO($args), TPARGS($argnames));
+#define trace_$name trace_ust_$name
+EOF
+}
+
+linetoh_end_ust()
+{
+# Clean up after UST headers which pollute the namespace
+cat EOF
+#undef mutex_lock
+#undef mutex_unlock
+EOF
+}
+
+linetoc_begin_ust()
+{
+cat EOF
+#include ust/marker.h
+#include trace.h
+EOF
+}
+
+linetoc_ust()
+{
+local name args argnames fmt
+name=$(get_name $1)
+args=$(get_args $1)
+argnames=$(get_argnames $1)
+fmt=$(get_fmt $1)
+
+cat EOF
+DEFINE_TRACE(ust_$name);
+
+static void ust_${name}_probe($args)
+{
+trace_mark(ust, $name, $fmt, $argnames);
+}
+EOF
+
+# Collect names for later
+names=$names $name
+}
+
+linetoc_end_ust()
+{
+cat EOF
+static void __attribute__((constructor)) trace_init(void)
+{
+EOF
+
+for name in $names; do
+cat EOF
+register_trace_ust_$name(ust_${name}_probe);
+EOF
+done
+
+echo }
+}
+
# Process stdin by calling begin, line, and end functions for the backend
convert()
{
@@ -267,7 +340,7 @@ tracetopy()
# Choose backend
case $1 in
---nop | --simple) backend=${1#--} ;;
+--nop | --simple | --ust) backend=${1#--} ;;
*) usage ;;
esac
shift
--
1.7.1
--
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