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| author | Steven Rostedt <rostedt@goodmis.org> | 2024-09-14 17:48:08 -0400 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-09-30 11:12:46 -0400 |
| commit | f1f36e22bee967db5e812a65e24389e54c46f3c2 (patch) | |
| tree | 6ca6497a81dbf3437901f77881c513443b8ba0f4 /kernel/trace/trace_functions_graph.c | |
| parent | 3c9880f3ab52b52b5b4e1850a70e80dd7329cb4c (diff) | |
| download | lwn-f1f36e22bee967db5e812a65e24389e54c46f3c2.tar.gz lwn-f1f36e22bee967db5e812a65e24389e54c46f3c2.zip | |
ftrace: Have calltime be saved in the fgraph storage
The calltime field in the shadow stack frame is only used by the function
graph tracer and profiler. But now that there's other users of the function
graph infrastructure, this adds overhead and wastes space on the shadow
stack. Move the calltime to the fgraph data storage, where the function
graph and profiler entry functions will save it in its own graph storage and
retrieve it in its exit functions.
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Link: https://lore.kernel.org/20240914214827.096968730@goodmis.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace_functions_graph.c')
| -rw-r--r-- | kernel/trace/trace_functions_graph.c | 60 |
1 files changed, 41 insertions, 19 deletions
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index bbd898f5a73c..5c1b150fbba3 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -127,13 +127,18 @@ static inline int ftrace_graph_ignore_irqs(void) return in_hardirq(); } +struct fgraph_times { + unsigned long long calltime; + unsigned long long sleeptime; /* may be optional! */ +}; + int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops) { unsigned long *task_var = fgraph_get_task_var(gops); struct trace_array *tr = gops->private; struct trace_array_cpu *data; - unsigned long *sleeptime; + struct fgraph_times *ftimes; unsigned long flags; unsigned int trace_ctx; long disabled; @@ -168,12 +173,18 @@ int trace_graph_entry(struct ftrace_graph_ent *trace, if (ftrace_graph_ignore_irqs()) return 0; - /* save the current sleep time if we are to ignore it */ - if (!fgraph_sleep_time) { - sleeptime = fgraph_reserve_data(gops->idx, sizeof(*sleeptime)); - if (sleeptime) - *sleeptime = current->ftrace_sleeptime; + if (fgraph_sleep_time) { + /* Only need to record the calltime */ + ftimes = fgraph_reserve_data(gops->idx, sizeof(ftimes->calltime)); + } else { + ftimes = fgraph_reserve_data(gops->idx, sizeof(*ftimes)); + if (ftimes) + ftimes->sleeptime = current->ftrace_sleeptime; } + if (!ftimes) + return 0; + + ftimes->calltime = trace_clock_local(); /* * Stop here if tracing_threshold is set. We only write function return @@ -247,19 +258,13 @@ void __trace_graph_return(struct trace_array *tr, } static void handle_nosleeptime(struct ftrace_graph_ret *trace, - struct fgraph_ops *gops) + struct fgraph_times *ftimes, + int size) { - unsigned long long *sleeptime; - int size; - - if (fgraph_sleep_time) - return; - - sleeptime = fgraph_retrieve_data(gops->idx, &size); - if (!sleeptime) + if (fgraph_sleep_time || size < sizeof(*ftimes)) return; - trace->calltime += current->ftrace_sleeptime - *sleeptime; + ftimes->calltime += current->ftrace_sleeptime - ftimes->sleeptime; } void trace_graph_return(struct ftrace_graph_ret *trace, @@ -268,9 +273,11 @@ void trace_graph_return(struct ftrace_graph_ret *trace, unsigned long *task_var = fgraph_get_task_var(gops); struct trace_array *tr = gops->private; struct trace_array_cpu *data; + struct fgraph_times *ftimes; unsigned long flags; unsigned int trace_ctx; long disabled; + int size; int cpu; ftrace_graph_addr_finish(gops, trace); @@ -280,7 +287,13 @@ void trace_graph_return(struct ftrace_graph_ret *trace, return; } - handle_nosleeptime(trace, gops); + ftimes = fgraph_retrieve_data(gops->idx, &size); + if (!ftimes) + return; + + handle_nosleeptime(trace, ftimes, size); + + trace->calltime = ftimes->calltime; local_irq_save(flags); cpu = raw_smp_processor_id(); @@ -297,6 +310,9 @@ void trace_graph_return(struct ftrace_graph_ret *trace, static void trace_graph_thresh_return(struct ftrace_graph_ret *trace, struct fgraph_ops *gops) { + struct fgraph_times *ftimes; + int size; + ftrace_graph_addr_finish(gops, trace); if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) { @@ -304,10 +320,16 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace, return; } - handle_nosleeptime(trace, gops); + ftimes = fgraph_retrieve_data(gops->idx, &size); + if (!ftimes) + return; + + handle_nosleeptime(trace, ftimes, size); + + trace->calltime = ftimes->calltime; if (tracing_thresh && - (trace->rettime - trace->calltime < tracing_thresh)) + (trace->rettime - ftimes->calltime < tracing_thresh)) return; else trace_graph_return(trace, gops); |