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Message-ID: <20160310012945.GC21119@sejong>
Date: Thu, 10 Mar 2016 10:29:45 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Jiri Olsa <jolsa@...nel.org>
CC: Steven Rostedt <rostedt@...dmis.org>,
lkml <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH 3/5] ftrace perf: Use ftrace_ops::private to store event
pointer
On Wed, Mar 09, 2016 at 09:46:43PM +0100, Jiri Olsa wrote:
> Having following commands running concurrently:
>
> # perf record -e ftrace:function -a -o krava.data sleep 10
> # perf record -e ftrace:function --filter 'ip == SyS_read' ls
>
> will end up in the latter one to fail on the filter rules
> and store all functions (in perf.data) as instructed by the
> first perf record instead of just SyS_read records.
>
> The reason for this is, that tracepoint code by default
> triggers all events that registered for the tracepoint.
>
> While ftrace:function is special because ftrace_ops
> itself carries a filter and only the event that owns
> ftrace_ops is eligible to be triggered.
>
> Fixing this by using ftrace_ops::private value to keep
> the perf_event pointer. This way we don't need to search
> for triggered event (as tracepoint handler does) and
> directly store sample.
>
> Suggested-by: Steven Rostedt <rostedt@...dmis.org>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
Acked-by: Namhyung Kim <namhyung@...nel.org>
Thanks,
Namhyung
> ---
> include/linux/perf_event.h | 3 +++
> kernel/events/core.c | 22 ++++++++++++++++++++++
> kernel/trace/trace_event_perf.c | 10 +++-------
> 3 files changed, 28 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index a9d8cab18b00..a330dc06d90d 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -1008,6 +1008,9 @@ extern void perf_tp_event(u64 addr, u64 count, void *record,
> int entry_size, struct pt_regs *regs,
> struct hlist_head *head, int rctx,
> struct task_struct *task);
> +void perf_function_event(struct perf_event *event,
> + void *record, int entry_size,
> + struct pt_regs *regs);
> extern void perf_bp_event(struct perf_event *event, void *data);
>
> #ifndef perf_misc_flags
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index ca68fdcf47ce..18da90859c17 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -7063,6 +7063,28 @@ static void perf_event_free_bpf_prog(struct perf_event *event)
> }
> }
>
> +#ifdef CONFIG_FUNCTION_TRACER
> +void perf_function_event(struct perf_event *event,
> + void *record, int entry_size,
> + struct pt_regs *regs)
> +
> +{
> + struct perf_sample_data data;
> + struct perf_raw_record raw = {
> + .size = entry_size,
> + .data = record,
> + };
> +
> + if (event->hw.state & PERF_HES_STOPPED)
> + return;
> +
> + perf_sample_data_init(&data, 0, 0);
> + data.raw = &raw;
> +
> + perf_swevent_event(event, 1, &data, regs);
> +}
> +#endif /* CONFIG_FUNCTION_TRACER */
> +
> #else
>
> static inline void perf_tp_register(void)
> diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
> index 0a3779bd18a1..087c811db04c 100644
> --- a/kernel/trace/trace_event_perf.c
> +++ b/kernel/trace/trace_event_perf.c
> @@ -328,14 +328,9 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
> struct ftrace_ops *ops, struct pt_regs *pt_regs)
> {
> struct ftrace_entry *entry;
> - struct hlist_head *head;
> struct pt_regs regs;
> int rctx;
>
> - head = this_cpu_ptr(event_function.perf_events);
> - if (hlist_empty(head))
> - return;
> -
> #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
> sizeof(u64)) - sizeof(u32))
>
> @@ -349,8 +344,8 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
>
> entry->ip = ip;
> entry->parent_ip = parent_ip;
> - perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
> - 1, ®s, head, NULL);
> + perf_function_event(ops->private, entry, ENTRY_SIZE, ®s);
> + perf_swevent_put_recursion_context(rctx);
>
> #undef ENTRY_SIZE
> }
> @@ -359,6 +354,7 @@ static int perf_ftrace_function_register(struct perf_event *event)
> {
> struct ftrace_ops *ops = &event->ftrace_ops;
>
> + ops->private = event;
> ops->flags |= FTRACE_OPS_FL_PER_CPU | FTRACE_OPS_FL_RCU;
> ops->func = perf_ftrace_function_call;
> return register_ftrace_function(ops);
> --
> 2.4.3
>
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