From: Steven Rostedt <rostedt@goodmis.org>
To: Changbin Du <changbin.du@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fgraph: Remove redundant ftrace_graph_notrace_addr() test
Date: Tue, 30 Jul 2019 12:15:27 -0400 [thread overview]
Message-ID: <20190730121527.13f600f5@gandalf.local.home> (raw)
In-Reply-To: <20190730140850.7927-1-changbin.du@gmail.com>
On Tue, 30 Jul 2019 22:08:50 +0800
Changbin Du <changbin.du@gmail.com> wrote:
> We already have tested it before. The second one should be removed.
> With this change, the performance should have little improvement.
>
> Fixes: 9cd2992f2d6c ("fgraph: Have set_graph_notrace only affect function_graph tracer")
Thanks! I think this should even be marked for stable. Not really a bad
bug, but a bug none the less.
-- Steve
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
> ---
> kernel/trace/trace_functions_graph.c | 17 +++++++----------
> 1 file changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index 69ebf3c2f1b5..78af97163147 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -137,6 +137,13 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
> if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))
> return 0;
>
> + /*
> + * Do not trace a function if it's filtered by set_graph_notrace.
> + * Make the index of ret stack negative to indicate that it should
> + * ignore further functions. But it needs its own ret stack entry
> + * to recover the original index in order to continue tracing after
> + * returning from the function.
> + */
> if (ftrace_graph_notrace_addr(trace->func)) {
> trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);
> /*
> @@ -155,16 +162,6 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
> if (ftrace_graph_ignore_irqs())
> return 0;
>
> - /*
> - * Do not trace a function if it's filtered by set_graph_notrace.
> - * Make the index of ret stack negative to indicate that it should
> - * ignore further functions. But it needs its own ret stack entry
> - * to recover the original index in order to continue tracing after
> - * returning from the function.
> - */
> - if (ftrace_graph_notrace_addr(trace->func))
> - return 1;
> -
> /*
> * Stop here if tracing_threshold is set. We only write function return
> * events to the ring buffer.
next prev parent reply other threads:[~2019-07-30 16:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 14:08 [PATCH] fgraph: Remove redundant ftrace_graph_notrace_addr() test Changbin Du
2019-07-30 16:15 ` Steven Rostedt [this message]
2019-07-31 10:31 ` Changbin Du
2019-07-31 11:58 ` Steven Rostedt
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