linux-kernel - Re: [PATCH v3 2/7] perf util: Create streams for managing top N hottest callchains

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Date:   Mon, 27 Apr 2020 12:10:52 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v3 2/7] perf util: Create streams for managing top N
 hottest callchains

On Mon, Apr 20, 2020 at 09:04:46AM +0800, Jin Yao wrote:
> We think the stream is a callchain which is aggregated by the LBR
> records from samples. By browsing the stream, we can understand
> the code flow.
> 
> The struct callchain_node represents one callchain and we use the
> callchain_node->hit to measure the hot level of this callchain.
> Higher is hotter.
> 
> Since in perf data file, there may be many callchains so we just
> need to focus on the top N hottest callchains. N is a user defined
> parameter or just a predefined default value.
> 
> This patch saves the top N hottest callchains in 'struct stream_node'
> type array, which is defined in a per event 'struct callchain_streams'.
> 
> So now we can get the per-event top N hottest callchains.
> 
>  v2:
>  ---
>  Use zfree in free_evsel_streams().
> 
> Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
> ---
>  tools/perf/util/callchain.c | 122 ++++++++++++++++++++++++++++++++++++
>  tools/perf/util/callchain.h |  16 +++++
>  2 files changed, 138 insertions(+)

SNIP

could this and all the other related code moved to separated object
like streams.c or such.. I think also the stuff from patch 1 could
go there, as it's specific only to this streams code

jirka