[PATCH] kselftests: ftrace: limit the executing time by reading from cached trace

From: Li Zhijian
Date: Mon Oct 18 2021 - 09:21:35 EST

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LKP/0day observed that kselftests/ftrace cannot finish within 1 hour on
a 96 cpus platform where it hangs in the line like:
'cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l'
subsystem-enable.tc

It seems that trace will keep growing during it's read by 'cat' command.
Consequently, trace becomes too large to finish reading.

replace 'cat trace' by:
$ sed -i 's/cat trace |/read_cached_trace |/g' $(find test.d -name "*.tc")

CC: Philip Li <philip.li@xxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxxxxx>
---
.../testing/selftests/ftrace/test.d/event/event-enable.tc | 6 +++---
.../testing/selftests/ftrace/test.d/event/event-no-pid.tc | 4 ++--
tools/testing/selftests/ftrace/test.d/event/event-pid.tc | 6 +++---
.../selftests/ftrace/test.d/event/subsystem-enable.tc | 6 +++---
.../selftests/ftrace/test.d/event/toplevel-enable.tc | 2 +-
.../selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc | 8 ++++----
.../selftests/ftrace/test.d/ftrace/fgraph-filter.tc | 4 ++--
.../ftrace/test.d/ftrace/func-filter-notrace-pid.tc | 8 ++++----
.../selftests/ftrace/test.d/ftrace/func-filter-pid.tc | 8 ++++----
tools/testing/selftests/ftrace/test.d/functions | 6 ++++++
.../selftests/ftrace/test.d/kprobe/kretprobe_args.tc | 2 +-
11 files changed, 33 insertions(+), 27 deletions(-)

diff --git a/tools/testing/selftests/ftrace/test.d/event/event-enable.tc b/tools/testing/selftests/ftrace/test.d/event/event-enable.tc
index cfe5bd2d4267..97d64ac407c9 100644
--- a/tools/testing/selftests/ftrace/test.d/event/event-enable.tc
+++ b/tools/testing/selftests/ftrace/test.d/event/event-enable.tc
@@ -18,7 +18,7 @@ echo 'sched:sched_switch' > set_event

yield

-count=`cat trace | grep sched_switch | wc -l`
+count=`read_cached_trace | grep sched_switch | wc -l`
if [ $count -eq 0 ]; then
fail "sched_switch events are not recorded"
fi
@@ -29,7 +29,7 @@ echo 1 > events/sched/sched_switch/enable

yield

-count=`cat trace | grep sched_switch | wc -l`
+count=`read_cached_trace | grep sched_switch | wc -l`
if [ $count -eq 0 ]; then
fail "sched_switch events are not recorded"
fi
@@ -40,7 +40,7 @@ echo 0 > events/sched/sched_switch/enable

yield

-count=`cat trace | grep sched_switch | wc -l`
+count=`read_cached_trace | grep sched_switch | wc -l`
if [ $count -ne 0 ]; then
fail "sched_switch events should not be recorded"
fi
diff --git a/tools/testing/selftests/ftrace/test.d/event/event-no-pid.tc b/tools/testing/selftests/ftrace/test.d/event/event-no-pid.tc
index 9933ed24f901..678f283044cb 100644
--- a/tools/testing/selftests/ftrace/test.d/event/event-no-pid.tc
+++ b/tools/testing/selftests/ftrace/test.d/event/event-no-pid.tc
@@ -23,12 +23,12 @@ fail() { #msg

count_pid() {
pid=$@
- cat trace | grep -v '^#' | sed -e 's/[^-]*-$[0-9]*$.*/\1/' | grep $pid | wc -l
+ read_cached_trace | grep -v '^#' | sed -e 's/[^-]*-$[0-9]*$.*/\1/' | grep $pid | wc -l
}

count_no_pid() {
pid=$1
- cat trace | grep -v '^#' | sed -e 's/[^-]*-$[0-9]*$.*/\1/' | grep -v $pid | wc -l
+ read_cached_trace | grep -v '^#' | sed -e 's/[^-]*-$[0-9]*$.*/\1/' | grep -v $pid | wc -l
}

enable_system() {
diff --git a/tools/testing/selftests/ftrace/test.d/event/event-pid.tc b/tools/testing/selftests/ftrace/test.d/event/event-pid.tc
index 7f5f97dffdc3..da7a5aa8f061 100644
--- a/tools/testing/selftests/ftrace/test.d/event/event-pid.tc
+++ b/tools/testing/selftests/ftrace/test.d/event/event-pid.tc
@@ -23,7 +23,7 @@ echo 1 > events/sched/sched_switch/enable

yield

-count=`cat trace | grep sched_switch | wc -l`
+count=`read_cached_trace | grep sched_switch | wc -l`
if [ $count -eq 0 ]; then
fail "sched_switch events are not recorded"
fi
@@ -38,7 +38,7 @@ echo 'sched:sched_switch' > set_event

yield

-count=`cat trace | grep sched_switch | grep -v "pid=$mypid" | wc -l`
+count=`read_cached_trace | grep sched_switch | grep -v "pid=$mypid" | wc -l`
if [ $count -ne 0 ]; then
fail "sched_switch events from other task are recorded"
fi
@@ -51,7 +51,7 @@ echo 1 > events/sched/sched_switch/enable

yield

-count=`cat trace | grep sched_switch | grep -v "pid=$mypid" | wc -l`
+count=`read_cached_trace | grep sched_switch | grep -v "pid=$mypid" | wc -l`
if [ $count -eq 0 ]; then
fail "sched_switch events from other task are not recorded"
fi
diff --git a/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc b/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc
index b1ede6249866..e21e923d8aa2 100644
--- a/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc
+++ b/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc
@@ -18,7 +18,7 @@ echo 'sched:*' > set_event

yield

-count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
+count=`read_cached_trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
if [ $count -lt 3 ]; then
fail "at least fork, exec and exit events should be recorded"
fi
@@ -29,7 +29,7 @@ echo 1 > events/sched/enable

yield

-count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
+count=`read_cached_trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
if [ $count -lt 3 ]; then
fail "at least fork, exec and exit events should be recorded"
fi
@@ -40,7 +40,7 @@ echo 0 > events/sched/enable

yield

-count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
+count=`read_cached_trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
if [ $count -ne 0 ]; then
fail "any of scheduler events should not be recorded"
fi
diff --git a/tools/testing/selftests/ftrace/test.d/event/toplevel-enable.tc b/tools/testing/selftests/ftrace/test.d/event/toplevel-enable.tc
index 93c10ea42a68..b24792987438 100644
--- a/tools/testing/selftests/ftrace/test.d/event/toplevel-enable.tc
+++ b/tools/testing/selftests/ftrace/test.d/event/toplevel-enable.tc
@@ -43,7 +43,7 @@ echo 0 > events/enable

yield

-count=`cat trace | grep -v ^# | wc -l`
+count=`read_cached_trace | grep -v ^# | wc -l`
if [ $count -ne 0 ]; then
fail "any of events should not be recorded"
fi
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc
index cf3ea42b12b0..157080f682bf 100644
--- a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc
+++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc
@@ -40,14 +40,14 @@ clear_trace
enable_tracing
sleep 1

-count=`cat trace | grep '()' | grep -v schedule | wc -l`
+count=`read_cached_trace | grep '()' | grep -v schedule | wc -l`

if [ $count -ne 0 ]; then
fail "Graph filtering not working with stack tracer?"
fi

# Make sure we did find something
-count=`cat trace | grep 'schedule()' | wc -l`
+count=`read_cached_trace | grep 'schedule()' | wc -l`
if [ $count -eq 0 ]; then
fail "No schedule traces found?"
fi
@@ -57,13 +57,13 @@ clear_trace
sleep 1

-count=`cat trace | grep '()' | grep -v schedule | wc -l`
+count=`read_cached_trace | grep '()' | grep -v schedule | wc -l`

if [ $count -ne 0 ]; then
fail "Graph filtering not working after stack tracer disabled?"
fi

-count=`cat trace | grep 'schedule()' | wc -l`
+count=`read_cached_trace | grep 'schedule()' | wc -l`
if [ $count -eq 0 ]; then
fail "No schedule traces found?"
fi
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc
index b3ccdaec2a61..930dfc06f4ba 100644
--- a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc
+++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc
@@ -26,13 +26,13 @@ enable_tracing
sleep 1
# search for functions (has "()" on the line), and make sure
# that only the schedule function was found
-count=`cat trace | grep '()' | grep -v schedule | wc -l`
+count=`read_cached_trace | grep '()' | grep -v schedule | wc -l`
if [ $count -ne 0 ]; then
fail "Graph filtering not working by itself?"
fi

# Make sure we did find something
-count=`cat trace | grep 'schedule()' | wc -l`
+count=`read_cached_trace | grep 'schedule()' | wc -l`
if [ $count -eq 0 ]; then
fail "No schedule traces found?"
fi
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc
index 80541964b927..1f08b7207d74 100644
--- a/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc
+++ b/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc
@@ -52,8 +52,8 @@ do_test() {
enable_tracing
yield

- count_pid=`cat trace | grep -v ^# | grep $PID | wc -l`
- count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l`
+ count_pid=`read_cached_trace | grep -v ^# | grep $PID | wc -l`
+ count_other=`read_cached_trace | grep -v ^# | grep -v $PID | wc -l`

# count_pid should be 0
if [ $count_pid -ne 0 -o $count_other -eq 0 ]; then
@@ -78,8 +78,8 @@ do_test() {
enable_tracing
yield

- count_pid=`cat trace | grep -v ^# | grep $PID | wc -l`
- count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l`
+ count_pid=`read_cached_trace | grep -v ^# | grep $PID | wc -l`
+ count_other=`read_cached_trace | grep -v ^# | grep -v $PID | wc -l`

# both should be zero
if [ $count_pid -ne 0 -o $count_other -ne 0 ]; then
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc
index 2f7211254529..30c218b849dc 100644
--- a/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc
+++ b/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc
@@ -52,8 +52,8 @@ do_test() {
enable_tracing
yield

- count_pid=`cat trace | grep -v ^# | grep $PID | wc -l`
- count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l`
+ count_pid=`read_cached_trace | grep -v ^# | grep $PID | wc -l`
+ count_other=`read_cached_trace | grep -v ^# | grep -v $PID | wc -l`

# count_other should be 0
if [ $count_pid -eq 0 -o $count_other -ne 0 ]; then
@@ -73,8 +73,8 @@ do_test() {
enable_tracing
yield

- count_pid=`cat trace | grep -v ^# | grep $PID | wc -l`
- count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l`
+ count_pid=`read_cached_trace | grep -v ^# | grep $PID | wc -l`
+ count_other=`read_cached_trace | grep -v ^# | grep -v $PID | wc -l`

# count_other should NOT be 0
if [ $count_pid -eq 0 -o $count_other -eq 0 ]; then
diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
index 000fd05e84b1..35d1d173d44b 100644
--- a/tools/testing/selftests/ftrace/test.d/functions
+++ b/tools/testing/selftests/ftrace/test.d/functions
@@ -175,3 +175,9 @@ ftrace_errlog_check() { # err-prefix command-with-error-pos-by-^ command-file
# " Command: " and "^\n" => 13
test $(expr 13 + $pos) -eq $N
}
+
+read_cached_trace() {
+ cp trace /tmp/cached_trace
+ cat /tmp/cached_trace
+ rm -f /tmp/cached_trace
+}
diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_args.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_args.tc
index 197cc2afd404..57b3b215122f 100644
--- a/tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_args.tc
+++ b/tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_args.tc
@@ -11,7 +11,7 @@ test -d events/kprobes/testprobe2
echo 1 > events/kprobes/testprobe2/enable
( echo "forked")

-cat trace | grep testprobe2 | grep -q "<- $FUNCTION_FORK"
+read_cached_trace | grep testprobe2 | grep -q "<- $FUNCTION_FORK"

echo 0 > events/kprobes/testprobe2/enable
echo '-:testprobe2' >> kprobe_events
--
2.31.1

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