On Tue, Jun 01, 2021 at 03:31:33PM +0800, Qu Wenruo wrote:
> Sometimes developers want trace dump for certain test cases.
>
> Normally I just add "trace-cmd" calls in "check", but it would be much
Heh, so do I!
> better to let fstests to support ftrace dumping.
>
> This patchset will add basic ftrace dumping support by:
>
> - Clear all buffers before running each test
> - Start tracing before running each test
> - End tracing after test finished
> - Copy the trace to "$seqres.trace" if needed
> The condition is either:
> * $KEEP_TRACE environment is set to "yes"
> * The test case failed
>
> Currently we only support the main ftrace buffer, but all supporting
> functions have support for ftrace instances, for later expansion.
I... did not know one could /have/ separate instances.
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> check | 12 +++++++-
> common/ftrace | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++
> common/rc | 1 +
> 3 files changed, 94 insertions(+), 1 deletion(-)
> create mode 100644 common/ftrace
>
> diff --git a/check b/check
> index ba192042..0a09dcf9 100755
> --- a/check
> +++ b/check
> @@ -801,7 +801,7 @@ function run_section()
> fi
>
> # really going to try and run this one
> - rm -f $seqres.out.bad
> + rm -f $seqres.out.bad $seqres.trace
>
> # check if we really should run it
> _expunge_test $seqnum
> @@ -839,6 +839,10 @@ function run_section()
> # to be reported for each test
> (echo 1 > $DEBUGFS_MNT/clear_warn_once) > /dev/null 2>&1
>
> + # Clear previous trace and start new trace
> + _clear_trace_buffers
> + _start_trace
How do you actually turn on specific tracepoints?
Or is the idea here to capture trace data for each test in a separate
file, and it's up to the ./check caller to set that up?
> +
> if [ "$DUMP_OUTPUT" = true ]; then
> _run_seq 2>&1 | tee $tmp.out
> # Because $? would get tee's return code
> @@ -848,6 +852,11 @@ function run_section()
> sts=$?
> fi
>
> + _end_trace
> + if [ "$KEEP_TRACE" == "yes" ]; then
> + _copy_trace "$seqres.trace"
> + fi
> +
> if [ -f core ]; then
> _dump_err_cont "[dumped core]"
> mv core $RESULT_BASE/$seqnum.core
> @@ -932,6 +941,7 @@ function run_section()
>
> # make sure we record the status of the last test we ran.
> if $err ; then
> + _copy_trace "$seqres.trace"
> bad="$bad $seqnum"
> n_bad=`expr $n_bad + 1`
> tc_status="fail"
> diff --git a/common/ftrace b/common/ftrace
> new file mode 100644
> index 00000000..36886484
> --- /dev/null
> +++ b/common/ftrace
> @@ -0,0 +1,82 @@
> +#
> +# Common ftrace related functions
> +#
New file needs a SPDX header.
> +
> +TRACE_DIR="/sys/kernel/debug/tracing"
> +
> +_clear_trace_buffers()
> +{
> + if [ ! -d "${TRACE_DIR}" ]; then
> + return
> + fi
> +
> + # Clear the main buffer
> + echo 0 > "${TRACE_DIR}/trace"
If one were already running trace-cmd record, will this mess up its
ability to collect trace data?
> +
> + # Clear each instance buffer
> + for i in $(ls "${TRACE_DIR}/instances"); do
> + echo 0 > "${i}/trace"
> + done
> +}
> +
> +_start_trace()
> +{
> + instance=$1
local instance="$1", please don't pollute the caller's environment.
> +
> + if [ ! -d "${TRACE_DIR}" ]; then
> + return
> + fi
> +
> + if [ -z "${instance}" ]; then
> + echo 1 > "${TRACE_DIR}/tracing_on"
> + else
> + mkdir -p "${TRACE_DIR}/instances/${instance}"
> + echo 1 > "${TRACE_DIR}/instances/${instance}/tracing_on"
> + fi
> +}
> +
> +_end_trace()
> +{
> + instance=$1
> +
> + if [ ! -d "${TRACE_DIR}" ]; then
> + return
> + fi
> +
> + if [ -z "${instance}" ]; then
> + echo 0 > "${TRACE_DIR}/tracing_on"
> + else
> + mkdir -p "${TRACE_DIR}/instances/${instance}"
Er, what's the logic here? Ensure that the instance exist so that we
can disable it?
--D
> + echo 0 > "${TRACE_DIR}/instances/${instance}/tracing_on"
> + fi
> +}
> +
> +_remove_empty_trace()
> +{
> + file="$1"
> + if [ ! -f "$file" ]; then
> + return
> + fi
> +
> + if [ -z "$(head -n 15 $file | sed '/^#/d')" ]; then
> + rm $file
> + fi
> +}
> +
> +_copy_trace()
> +{
> + dest="$1"
> + instance="$2"
> +
> + if [ ! -d "${TRACE_DIR}" ]; then
> + return
> + fi
> +
> + if [ -z "${instance}" ]; then
> + cp "${TRACE_DIR}/trace" "$dest"
> + elif [ -d "${TRACE_DIR}/instances/${instance}" ]; then
> + cp "${TRACE_DIR}/instances/${instance}/trace" "$dest"
> + fi
> +
> + _remove_empty_trace "$dest"
> +}
> diff --git a/common/rc b/common/rc
> index 919028ef..f9de1517 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -3,6 +3,7 @@
> # Copyright (c) 2000-2006 Silicon Graphics, Inc. All Rights Reserved.
>
> . common/config
> +. common/ftrace
>
> BC=$(which bc 2> /dev/null) || BC=
>
> --
> 2.31.1
>
