linux-kernel - Re: [PATCH v3 1/6] perf tools: Derive trigger class from auxtrace

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Date:	Mon, 18 Apr 2016 10:23:46 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	Jiri Olsa <jolsa@...hat.com>
CC:	<acme@...nel.org>, <linux-kernel@...r.kernel.org>,
	<pi3orama@....com>, Adrian Hunter <adrian.hunter@...el.com>,
	He Kuang <hekuang@...wei.com>, Jiri Olsa <jolsa@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Zefan Li <lizefan@...wei.com>,
	"Arnaldo Carvalho de Melo" <acme@...hat.com>
Subject: Re: [PATCH v3 1/6] perf tools: Derive trigger class from
 auxtrace_snapshot



On 2016/4/17 19:50, Jiri Olsa wrote:
> On Fri, Apr 15, 2016 at 06:20:15PM +0000, Wang Nan wrote:
>> Create a new class named 'trigger' to model the state of a trigger and
>> implement auxtrace_snapshot with it.
>>
>> auxtrace_record__snapshot_started and auxtrace_snapshot_err are absorbed.
>>
>> 'trigger' defines 4 state transitioning functions ('on', 'released',
>> 'toggle' and 'colddown') and 2 state query function ('is_released') and
>> ('is_toggled'). The state 'ON' and 'OFF' take higher priority than
>> 'RELEASED' and 'TOGGLED'.  A trigger must be 'on' before 'enable' and
>> 'disable' take effect. A trigger can be colddown after being triggered.
> what's the COLDDOWN state for?

COLDDOWN is for auxtrace_record__snapshot_started. Once signal received,
auxtrace subsystem doesn't process following signal, until
record__read_auxtrace_snapshot finished successful. Mapping to trigger,
once the state of a trigger moves to 'TRIGGERED', there must be a state
neither RELEASED nor ERROR, which disallow triggering, but allow transiting
to RELEASED.


> could you please document all the transitions of this state machine
> in the change log and the trigger.h file?

Will do. Thank you.

> thanks,
> jirka