diff options
| author | Yun Zhou <yun.zhou@windriver.com> | 2026-09-24 11:01:08 +0800 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2026-10-15 20:12:49 -0400 |
| commit | 1054e526ce4e428562b8084f6ee4ef1721a5675c (patch) | |
| tree | d37c9aeacb666194d8b07c81ec183d2abec6a2e8 /kernel/trace | |
| parent | 188a5bfd876a46d4e465542683f83079edf537bf (diff) | |
ftrace: Add max field to function profiler stats
The function profiler (trace_stat/function<cpu>) reports Hit, Time,
Avg and s^2 per function. Add a "max" field recording the maximum
single-call duration, which is valuable for real-time tuning and for
investigating occasional latency spikes.
Like Time/Avg, it honors the graph-time and sleep-time options, so it
reflects entry-to-return wall-clock latency.
Link: https://patch.msgid.link/20260924030108.2673654-1-yun.zhou@windriver.com
Signed-off-by: Yun Zhou <yun.zhou@windriver.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/ftrace.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 673a54fdf392..98535f5533db 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -428,6 +428,7 @@ struct ftrace_profile { #ifdef CONFIG_FUNCTION_GRAPH_TRACER unsigned long long time; unsigned long long time_squared; + unsigned long long time_max; #endif }; @@ -530,9 +531,9 @@ static int function_stat_headers(struct seq_file *m) { #ifdef CONFIG_FUNCTION_GRAPH_TRACER seq_puts(m, " Function " - "Hit Time Avg s^2\n" + "Hit Time Avg s^2 max\n" " -------- " - "--- ---- --- ---\n"); + "--- ---- --- --- ---\n"); #else seq_puts(m, " Function Hit\n" " -------- ---\n"); @@ -613,6 +614,8 @@ static int function_stat_show(struct seq_file *m, void *v) trace_print_graph_duration(avg, &s); trace_seq_puts(&s, " "); trace_print_graph_duration(stddev, &s); + trace_seq_puts(&s, " "); + trace_print_graph_duration(rec->time_max, &s); trace_print_seq(m, &s); #endif seq_putc(m, '\n'); @@ -920,6 +923,8 @@ static void profile_graph_return(struct ftrace_graph_ret *trace, if (rec) { rec->time += calltime; rec->time_squared += calltime * calltime; + if (calltime > rec->time_max) + rec->time_max = calltime; } } |