* [PATCH v2 1/2] tracing/histogram: Document hist trigger variables
2021-10-28 19:57 [PATCH v2 0/2] tracing/kselftest: histogram trigger expression tests Kalesh Singh
@ 2021-10-28 19:57 ` Kalesh Singh
2021-10-28 19:57 ` [PATCH v6 2/2] tracing/selftests: Add tests for hist trigger expression parsing Kalesh Singh
1 sibling, 0 replies; 4+ messages in thread
From: Kalesh Singh @ 2021-10-28 19:57 UTC (permalink / raw)
Cc: surenb, hridya, namhyung, kernel-team, rostedt, mhiramat,
Kalesh Singh, Ingo Molnar, Shuah Khan, linux-kernel,
linux-kselftest
Update the tracefs README to describe how hist trigger variables
can be created.
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
---
Changes in v2:
- Add Masami's Acked-by.
kernel/trace/trace.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bc677cd64224..c41b3786401d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5628,6 +5628,7 @@ static const char readme_msg[] =
#ifdef CONFIG_HIST_TRIGGERS
" hist trigger\t- If set, event hits are aggregated into a hash table\n"
"\t Format: hist:keys=<field1[,field2,...]>\n"
+ "\t [:<var1>=<field|var_ref|numeric_literal>[,<var2>=...]]\n"
"\t [:values=<field1[,field2,...]>]\n"
"\t [:sort=<field1[,field2,...]>]\n"
"\t [:size=#entries]\n"
@@ -5639,6 +5640,16 @@ static const char readme_msg[] =
"\t common_timestamp - to record current timestamp\n"
"\t common_cpu - to record the CPU the event happened on\n"
"\n"
+ "\t A hist trigger variable can be:\n"
+ "\t - a reference to a field e.g. x=current_timestamp,\n"
+ "\t - a reference to another variable e.g. y=$x,\n"
+ "\t - a numeric literal: e.g. ms_per_sec=1000,\n"
+ "\t - an arithmetic expression: e.g. time_secs=current_timestamp/1000\n"
+ "\n"
+ "\t hist trigger aritmethic expressions support addition(+), subtraction(-),\n"
+ "\t multiplication(*) and division(/) operators. An operand can be either a\n"
+ "\t variable reference, field or numeric literal.\n"
+ "\n"
"\t When a matching event is hit, an entry is added to a hash\n"
"\t table using the key(s) and value(s) named, and the value of a\n"
"\t sum called 'hitcount' is incremented. Keys and values\n"
--
2.33.0.1079.g6e70778dc9-goog
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v6 2/2] tracing/selftests: Add tests for hist trigger expression parsing
2021-10-28 19:57 [PATCH v2 0/2] tracing/kselftest: histogram trigger expression tests Kalesh Singh
2021-10-28 19:57 ` [PATCH v2 1/2] tracing/histogram: Document hist trigger variables Kalesh Singh
@ 2021-10-28 19:57 ` Kalesh Singh
2021-10-29 5:27 ` Masami Hiramatsu
1 sibling, 1 reply; 4+ messages in thread
From: Kalesh Singh @ 2021-10-28 19:57 UTC (permalink / raw)
Cc: surenb, hridya, namhyung, kernel-team, rostedt, mhiramat,
Kalesh Singh, Ingo Molnar, Shuah Khan, linux-kernel,
linux-kselftest
Add tests for the parsing of hist trigger expressions; and to
validate expression evaluation.
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
Changes in v6:
- Read the expression result from the trigger file,
instead of creating a histogram to print the value.
Changes in v5:
- Add README pattern to requires tag, per Masami
Changes in v3:
- Remove .sym-offset error check tests
Changes in v2:
- Add Namhyung's Reviewed-by
- Update comment to clarify err_pos in "Too many subexpressions" test
.../trigger/trigger-hist-expressions.tc | 65 +++++++++++++++++++
1 file changed, 65 insertions(+)
create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc
diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc
new file mode 100644
index 000000000000..33eb79589b32
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc
@@ -0,0 +1,65 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test histogram expression parsing
+# requires: set_event events/sched/sched_process_fork/trigger events/sched/sched_process_fork/hist error_log "<var1>=<field|var_ref|numeric_literal>":README
+
+
+fail() { #msg
+ echo $1
+ exit_fail
+}
+
+test_hist_expr() { # test_name expression expected_val
+ trigger="events/sched/sched_process_fork/trigger"
+
+ reset_trigger_file $trigger
+
+ echo "Test hist trigger expressions - $1"
+
+ echo "hist:keys=common_pid:x=$2" > $trigger
+
+ for i in `seq 1 10` ; do ( echo "forked" > /dev/null); done
+
+ x=`grep -o 'x=[[:digit:]]*' $trigger | awk -F= '{ print $2 }'`
+ actual=$(( x + 0 )) # To print negative numbers correctly
+
+ if [ $actual != $3 ]; then
+ fail "Failed hist trigger expression evaluation: Expression: $2 Expected: $3, Actual: $actual"
+ fi
+
+ reset_trigger_file $trigger
+}
+
+check_error() { # test_name command-with-error-pos-by-^
+ trigger="events/sched/sched_process_fork/trigger"
+
+ echo "Test hist trigger expressions - $1"
+ ftrace_errlog_check 'hist:sched:sched_process_fork' "$2" $trigger
+}
+
+test_hist_expr "Variable assignment" "123" "123"
+
+test_hist_expr "Subtraction not associative" "16-8-4-2" "2"
+
+test_hist_expr "Division not associative" "64/8/4/2" "1"
+
+test_hist_expr "Same precedence operators (+,-) evaluated left to right" "16-8+4+2" "14"
+
+test_hist_expr "Same precedence operators (*,/) evaluated left to right" "4*3/2*2" "12"
+
+test_hist_expr "Multiplication evaluated before addition/subtraction" "4+3*2-2" "8"
+
+test_hist_expr "Division evaluated before addition/subtraction" "4+6/2-2" "5"
+
+# Division by zero returns -1
+test_hist_expr "Handles division by zero" "3/0" "-1"
+
+# err pos for "too many subexpressions" is dependent on where
+# the last subexpression was detected. This can vary depending
+# on how the expression tree was generated.
+check_error "Too many subexpressions" 'hist:keys=common_pid:x=32+^10*3/20-4'
+check_error "Too many subexpressions" 'hist:keys=common_pid:x=^1+2+3+4+5'
+
+check_error "Unary minus not supported in subexpression" 'hist:keys=common_pid:x=-(^1)+2'
+
+exit 0
--
2.33.0.1079.g6e70778dc9-goog
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