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

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Message-ID: <3ecf60b3-1304-4a33-1bec-52eb580c0a00@linux.intel.com>
Date:   Tue, 28 Apr 2020 16:12:04 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.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

Hi Jiri,

On 4/27/2020 6:10 PM, Jiri Olsa wrote:
> 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
> 

That's fine. I will move the related codes to a new streams.c/streams.h.

Thanks
Jin Yao