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Subject: Re: [PATCH 02/17] perf tools: Add evlist channel helpers
To: Arnaldo Carvalho de Melo <acme@kernel.org>
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CC: <arnaldo.melo@gmail.com>, <linux-kernel@vger.kernel.org>,
        He Kuang <hekuang@huawei.com>,
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        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
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From: "Wangnan (F)" <wangnan0@huawei.com>
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Date: Wed, 18 May 2016 11:27:43 +0800
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On 2016/5/13 21:05, Arnaldo Carvalho de Melo wrote:
> Em Fri, May 13, 2016 at 07:55:59AM +0000, Wang Nan escreveu:
>> In this commit sereval helpers are introduced to support the principle
>                   several
>
>> of channel. Channels hold different groups of evsels which configured
>> differently. It will be used for overwritable evsels, which allows perf
> why not use multiple evlists? An "evlist" is a "list of evsels", why do
> we need yet another way of grouping evlists?
>
> - Arnaldo
>

There's an assumption all over perf that there's only one evlist: in 
'struct record'
there's an 'evlist' pointer, in 'struct session' there's also an 
'evlist' pointer.
Trying to change them to an array results in 181 errors, so I think 
fundamentally
moving to multiple evlists is nearly impossible.

Now I'm thinking introducing auxiliary evlists to perf record. We still 
obey one
evlist assumption, only creates separated evlists for mmap.

Thank you.