linux-kernel - Re: [PATCH v3 3/5] perf tools: Fix dynamic sort keys to sort properly

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Date:	Wed, 6 Jan 2016 20:06:43 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Wang Nan <wangnan0@...wei.com>
Subject: Re: [PATCH v3 3/5] perf tools: Fix dynamic sort keys to sort properly

Em Wed, Jan 06, 2016 at 09:54:59AM +0900, Namhyung Kim escreveu:
> Currently, the dynamic sort keys compares trace data using memcmp().
> But for output sorting, it should check data size and compare by word.
> Also it sorted strings in reverse order, fix it.

Can this be broken down in two patches? This is complex code, lets try
to make it as bisectable as possible.

- Arnaldo

> 
> Before)
> 
>   $ perf report -F overhead -s prev_pid,next_pid
>   ...
>   # Overhead    prev_pid    next_pid
>   # ........  ..........  ..........
>   #
>        0.39%         490           0
>        9.12%         225           0
>        0.04%         224           0
>        0.51%         731         189
>        0.08%         731           3
>        0.12%         731           0
>        4.82%         729           0
>        0.08%        1229           0
>        0.20%         715           0
>        4.78%         189         225
>   ...
> 
> After)
> 
>   $ perf report -F overhead -s prev_pid,next_pid
>   ...
>   # Overhead    prev_pid    next_pid
>   # ........  ..........  ..........
>   #
>        0.43%           0           7
>        0.04%           0          11
>        0.04%           0          12
>        0.08%           0          14
>        0.04%           0          17
>        0.08%           0          19
>        0.04%           0          22
>        0.04%           0          27
>        0.04%           0          37
>        0.04%           0          42
>   ...
> 
> Reported-by: Arnaldo Carvalho de Melo <acme@...nel.org>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/sort.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
> index 9618a64875c0..264d2b630549 100644
> --- a/tools/perf/util/sort.c
> +++ b/tools/perf/util/sort.c
> @@ -1798,6 +1798,51 @@ static int64_t __sort__hde_cmp(struct perf_hpp_fmt *fmt,
>  	return memcmp(a->raw_data + offset, b->raw_data + offset, size);
>  }
>  
> +static int64_t __sort__hde_sort(struct perf_hpp_fmt *fmt,
> +				struct hist_entry *a, struct hist_entry *b)
> +{
> +	struct hpp_dynamic_entry *hde;
> +	struct format_field *field;
> +	unsigned offset, size;
> +	int64_t *a64, *b64;
> +	int32_t *a32, *b32;
> +	int16_t *a16, *b16;
> +
> +	hde = container_of(fmt, struct hpp_dynamic_entry, hpp);
> +
> +	field = hde->field;
> +	if (field->flags & FIELD_IS_DYNAMIC) {
> +		unsigned long long dyn;
> +
> +		pevent_read_number_field(field, a->raw_data, &dyn);
> +		offset = dyn & 0xffff;
> +		size = (dyn >> 16) & 0xffff;
> +	} else {
> +		offset = field->offset;
> +		size = field->size;
> +	}
> +
> +	if (field->flags & FIELD_IS_STRING)
> +		return strcmp(b->raw_data + offset, a->raw_data + offset);
> +
> +	switch (size) {
> +	case 8:
> +		a64 = a->raw_data + offset;
> +		b64 = b->raw_data + offset;
> +		return *b64 - *a64;
> +	case 4:
> +		a32 = a->raw_data + offset;
> +		b32 = b->raw_data + offset;
> +		return *b32 - *a32;
> +	case 2:
> +		a16 = a->raw_data + offset;
> +		b16 = b->raw_data + offset;
> +		return *b16 - *a16;
> +	default:
> +		return memcmp(b->raw_data + offset, a->raw_data + offset, size);
> +	}
> +}
> +
>  bool perf_hpp__is_dynamic_entry(struct perf_hpp_fmt *fmt)
>  {
>  	return fmt->cmp == __sort__hde_cmp;
> @@ -1826,7 +1871,7 @@ __alloc_dynamic_entry(struct perf_evsel *evsel, struct format_field *field)
>  
>  	hde->hpp.cmp = __sort__hde_cmp;
>  	hde->hpp.collapse = __sort__hde_cmp;
> -	hde->hpp.sort = __sort__hde_cmp;
> +	hde->hpp.sort = __sort__hde_sort;
>  
>  	INIT_LIST_HEAD(&hde->hpp.list);
>  	INIT_LIST_HEAD(&hde->hpp.sort_list);
> -- 
> 2.6.4
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