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From: Jiri Olsa <jolsa@redhat.com>
To: Daniel Xu <dxu@dxuuu.xyz>
Cc: bpf@vger.kernel.org, songliubraving@fb.com, yhs@fb.com,
	andriin@fb.com, peterz@infradead.org, mingo@redhat.com,
	acme@kernel.org, ast@fb.com, alexander.shishkin@linux.intel.com,
	namhyung@kernel.org, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH bpf-next 1/5] perf/core: Add PERF_FORMAT_LOST read_format
Date: Tue, 24 Sep 2019 10:33:42 +0200
Message-ID: <20190924083342.GA21640@krava> (raw)
In-Reply-To: <20190917133056.5545-2-dxu@dxuuu.xyz>

On Tue, Sep 17, 2019 at 06:30:52AM -0700, Daniel Xu wrote:

SNIP

> +	PERF_FORMAT_MAX = 1U << 5,		/* non-ABI */
>  };
>  
>  #define PERF_ATTR_SIZE_VER0	64	/* sizeof first published struct */
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 0463c1151bae..ee08d3ed6299 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -1715,6 +1715,9 @@ static void __perf_event_read_size(struct perf_event *event, int nr_siblings)
>  	if (event->attr.read_format & PERF_FORMAT_ID)
>  		entry += sizeof(u64);
>  
> +	if (event->attr.read_format & PERF_FORMAT_LOST)
> +		entry += sizeof(u64);
> +
>  	if (event->attr.read_format & PERF_FORMAT_GROUP) {
>  		nr += nr_siblings;
>  		size += sizeof(u64);
> @@ -4734,6 +4737,24 @@ u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
>  }
>  EXPORT_SYMBOL_GPL(perf_event_read_value);
>  
> +static struct pmu perf_kprobe;
> +static u64 perf_event_lost(struct perf_event *event)
> +{
> +	struct ring_buffer *rb;
> +	u64 lost = 0;
> +
> +	rcu_read_lock();
> +	rb = rcu_dereference(event->rb);
> +	if (likely(!!rb))
> +		lost += local_read(&rb->lost);
> +	rcu_read_unlock();
> +
> +	if (event->attr.type == perf_kprobe.type)
> +		lost += perf_kprobe_missed(event);

not sure what was the peterz's suggestion, but here you are mixing
ring buffer's lost count with kprobes missed count, seems wrong

maybe we could add PERF_FORMAT_KPROBE_MISSED

jirka

  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-17 13:30 [PATCH bpf-next 0/5] " Daniel Xu
2019-09-17 13:30 ` [PATCH bpf-next 1/5] perf/core: " Daniel Xu
2019-09-17 14:32   ` kbuild test robot
2019-09-17 15:22   ` kbuild test robot
2019-09-24  8:33   ` Jiri Olsa [this message]
2019-09-27 21:28     ` Daniel Xu
2019-10-25 18:19       ` Daniel Xu
2019-10-28  9:12     ` Peter Zijlstra
2019-09-17 13:30 ` [PATCH bpf-next 2/5] perf/core: Sync perf_event.h to tools Daniel Xu
2019-09-17 13:30 ` [PATCH bpf-next 3/5] libbpf: Add helpers to extract perf fd from bpf_link Daniel Xu
2019-09-17 13:30 ` [PATCH bpf-next 4/5] libbpf: Set read_format PERF_FORMAT_LOST on kprobe perf fds Daniel Xu
2019-09-17 13:30 ` [PATCH bpf-next 5/5] libbpf: Add selftest for PERF_FORMAT_LOST perf read_format Daniel Xu
2019-09-17 15:14 [PATCH bpf-next 1/5] perf/core: Add PERF_FORMAT_LOST read_format Daniel Xu

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