Date:   Mon, 17 Oct 2022 16:25:02 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Steven Rostedt <rostedt@...dmis.org>, Shuah Khan <shuah@...nel.org>
Cc:     <linux-kernel@...r.kernel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Akanksha J N <akanksha@...ux.vnet.ibm.com>
Subject: [PATCH] selftests/ftrace: Limit number of lines processed in 'trace'

On very large machines, ftracetest can seem to hang or otherwise take a
very long time to complete individual tests. This can be attributed to
statements that try to process the entire contents of 'trace'.

Limit the number of lines processed from 'trace' to resolve this. Apart
from the change in test.d/functions to add TRACENL, this commit is the
result of running the below command (and fixing some whitespace errors):
  grep -l -R 'cat trace |' -- ./tools/testing/selftests/ftrace/test.d/ | \
	xargs -n 1 sed --in-place -e "s/cat trace |/head -\$\{TRACENL\} trace |/g"

Reported-by: Akanksha J N <akanksha@...ux.vnet.ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
---
 .../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           | 3 +++
 .../selftests/ftrace/test.d/kprobe/kretprobe_args.tc      | 2 +-
 11 files changed, 30 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 cfe5bd2d426794..0a2d236cd94822 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=`head -${TRACENL} 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=`head -${TRACENL} 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=`head -${TRACENL} 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 9933ed24f90124..711301a36b69b6 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 $pid | wc -l
+    head -${TRACENL} 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 $pid | wc -l
+    head -${TRACENL} 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 7f5f97dffdc3dd..8ecdc211ac0432 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=`head -${TRACENL} 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=$mypid" | wc -l`
+count=`head -${TRACENL} 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=$mypid" | wc -l`
+count=`head -${TRACENL} 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 b1ede624986676..d5a1faff71773c 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 $5 }' | sort -u | wc -l`
+count=`head -${TRACENL} 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 $5 }' | sort -u | wc -l`
+count=`head -${TRACENL} 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 $5 }' | sort -u | wc -l`
+count=`head -${TRACENL} 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 93c10ea42a6868..1b7d4700a21b1e 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=`head -${TRACENL} 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 cf3ea42b12b09f..2861aaaec3908b 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=`head -${TRACENL} 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=`head -${TRACENL} 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=`head -${TRACENL} 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=`head -${TRACENL} trace | grep 'schedule()' | wc -l`
 if [ $count -eq 0 ]; then
     fail "No schedule traces found?"
 fi
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc
index b3ccdaec2a61ba..679eed983ef931 100644
--- a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc
+++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc
@@ -26,13 +26,13 @@ enable_tracing
 sleep 1
 # search for functions (has "()" on the line), and make sure
 # that only the schedule function was found
-count=`cat trace | grep '()' | grep -v schedule | wc -l`
+count=`head -${TRACENL} 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=`head -${TRACENL} 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 80541964b9270b..088ec11d87fa46 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 $PID | wc -l`
+    count_pid=`head -${TRACENL} trace | grep -v ^# | grep $PID | wc -l`
+    count_other=`head -${TRACENL} 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 $PID | wc -l`
+    count_pid=`head -${TRACENL} trace | grep -v ^# | grep $PID | wc -l`
+    count_other=`head -${TRACENL} 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 2f7211254529ba..fed002ed262b1d 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 $PID | wc -l`
+    count_pid=`head -${TRACENL} trace | grep -v ^# | grep $PID | wc -l`
+    count_other=`head -${TRACENL} 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 $PID | wc -l`
+    count_pid=`head -${TRACENL} trace | grep -v ^# | grep $PID | wc -l`
+    count_other=`head -${TRACENL} 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 5f6cbec847fc99..6a9a794bde11f7 100644
--- a/tools/testing/selftests/ftrace/test.d/functions
+++ b/tools/testing/selftests/ftrace/test.d/functions
@@ -174,6 +174,9 @@ yield() {
 FUNCTION_FORK=`(if grep '\bkernel_clone\b' /proc/kallsyms > /dev/null; then
                 echo kernel_clone; else echo '_do_fork'; fi)`
 
+# TRACENL controls the number of lines processed from the 'trace' file
+TRACENL=3000
+
 # Since probe event command may include backslash, explicitly use printf "%s"
 # to NOT interpret it.
 ftrace_errlog_check() { # err-prefix command-with-error-pos-by-^ command-file
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 197cc2afd4046b..804d6a6e3a99dd 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 "<- $FUNCTION_FORK"
+head -${TRACENL} trace | grep testprobe2 | grep -q "<- $FUNCTION_FORK"
 
 echo 0 > events/kprobes/testprobe2/enable
 echo '-:testprobe2' >> kprobe_events

base-commit: 6c0f39e87b6ab1a3009e3a49d3e6f6db8dc756a8
-- 
2.38.0

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