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Date: Wed, 24 Feb 2016 15:21:46 +0100
From: Jiri Olsa <jolsa@redhat.com>
To: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Brendan Gregg <brendan.d.gregg@gmail.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Cody P Schafer <dev@codyps.com>,
        "David S. Miller" <davem@davemloft.net>, He Kuang <hekuang@huawei.com>,
        =?iso-8859-1?Q?J=E9r=E9mie?= Galarneau 
	<jeremie.galarneau@efficios.com>,
        Jiri Olsa <jolsa@kernel.org>, Kirill Smelkov <kirr@nexedi.com>,
        Li Zefan <lizefan@huawei.com>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, pi3orama@163.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 18/48] perf tools: Only validate is_pos for tracking
 evsels
Message-ID: <20160224142146.GD27710@krava.redhat.com>
References: <1456132275-98875-1-git-send-email-wangnan0@huawei.com>
 <1456132275-98875-19-git-send-email-wangnan0@huawei.com>
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On Mon, Feb 22, 2016 at 09:10:45AM +0000, Wang Nan wrote:
> is_pos only useful for tracking events (fork, mmap, exit, ...).
> Perf collects those events through evsel with 'tracking' set.
> Therefore, there's no need to validate every is_pos against
> evlist->is_pos.
> 
> This patch is required after perf support PERF_SAMPLE_TAILSIZE.
> Since there an extra u64 at the end of this type of evsels, is_pos
> for evsel with PERF_SAMPLE_TAILSIZE setting is different from other
> evsels.
> 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> Signed-off-by: He Kuang <hekuang@huawei.com>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Zefan Li <lizefan@huawei.com>
> Cc: pi3orama@163.com
> ---
>  tools/perf/util/evlist.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index c42e196..fef465a 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -1274,8 +1274,15 @@ bool perf_evlist__valid_sample_type(struct perf_evlist *evlist)
>  		return false;
>  
>  	evlist__for_each(evlist, pos) {
> -		if (pos->id_pos != evlist->id_pos ||
> -		    pos->is_pos != evlist->is_pos)
> +		if (pos->id_pos != evlist->id_pos)
> +			return false;
> +		/*
> +		 * Only tracking events needs is_pos. Those events are
> +		 * collected if evsel->tracking is selected.
> +		 * For other evsel, is_pos is useless for other evsels,

typo in comment above ^^^ using twice 'other evsel'

> +		 * so skip validating them.
> +		 */
> +		if (pos->tracking && pos->is_pos != evlist->is_pos)
>  			return false;
>  	}
>  
> -- 
> 1.8.3.4
>