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From: Namhyung Kim <namhyung@kernel.org>
To: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: rostedt@goodmis.org, tglx@linutronix.de, mhiramat@kernel.org,
	vedang.patel@intel.com, linux-kernel@vger.kernel.org,
	linux-rt-users@vger.kernel.org, kernel-team@lge.com
Subject: Re: [PATCH 16/32] tracing: Add variable support to hist triggers
Date: Wed, 19 Jul 2017 10:07:43 +0900	[thread overview]
Message-ID: <20170719010743.GA10107@sejong> (raw)
In-Reply-To: <990cbe4e75a04b81e94220751501d8adeec26804.1498510759.git.tom.zanussi@linux.intel.com>

Hi Tom,

On Mon, Jun 26, 2017 at 05:49:17PM -0500, Tom Zanussi wrote:
> Add support for saving the value of a current event's event field by
> assigning it to a variable that can be read by a subsequent event.
> 
> The basic syntax for saving a variable is to simply prefix a unique
> variable name not corresponding to any keyword along with an '=' sign
> to any event field.
> 
> Both keys and values can be saved and retrieved in this way:
> 
>     # echo 'hist:keys=next_pid:vals=ts0=common_timestamp ...
>     # echo 'hist:key=timer_pid=common_pid ...'
> 
> If a variable isn't a key variable or prefixed with 'vals=', the
> associated event field will be saved in a variable but won't be summed
> as a value:
> 
>     # echo 'hist:keys=next_pid:ts1=common_timestamp:...
> 
> Multiple variables can be assigned at the same time:
> 
>     # echo 'hist:keys=pid:vals=ts0=common_timestamp,b=field1,field2 ...
> 
> Multiple (or single) variables can also be assigned at the same time
> using separate assignments:
> 
>     # echo 'hist:keys=pid:vals=ts0=common_timestamp:b=field1:c=field2 ...

It seems the variable definition can be hard to read if multiple
variables with expression are used.  I think it'd be better to make it
clear what's the key and the values by separating the variable
definition.  For example, the above example can be written as

  # echo 'hist:key=pid:val=ts0:ts0=$common_timestamp:b=field1:...'

I know this is not a good example since the 'ts0' is a simple
reference to the timestamp but it can be more complex..

What do you think?

Thanks,
Namhyung


> 
> Variables set as above can be used by being referenced from another
> event, as described in a subsequent patch.
> 
> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>

  reply	other threads:[~2017-07-19  1:07 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-26 22:49 [PATCH 00/32] tracing: Inter-event (e.g. latency) support Tom Zanussi
2017-06-26 22:49 ` [PATCH 01/32] tracing: Add hist_field_name() accessor Tom Zanussi
2017-07-13  6:49   ` Piotr Gregor
2017-07-13 14:41     ` Tom Zanussi
2017-07-14  2:19   ` Namhyung Kim
2017-06-26 22:49 ` [PATCH 02/32] tracing: Reimplement log2 Tom Zanussi
2017-07-14  2:33   ` Namhyung Kim
2017-07-14 16:13     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 03/32] ring-buffer: Add interface for setting absolute time stamps Tom Zanussi
2017-07-14  5:25   ` Namhyung Kim
2017-07-14 16:14     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 04/32] ring-buffer: Redefine the unimplemented RINGBUF_TIME_TIME_STAMP Tom Zanussi
2017-07-02  8:51   ` Joel Fernandes (Google)
2017-06-26 22:49 ` [PATCH 05/32] tracing: Give event triggers access to ring_buffer_event Tom Zanussi
2017-06-26 22:49 ` [PATCH 06/32] tracing: Add ring buffer event param to hist field functions Tom Zanussi
2017-06-26 22:49 ` [PATCH 07/32] tracing: Increase tracing map KEYS_MAX size Tom Zanussi
2017-06-26 22:49 ` [PATCH 08/32] tracing: Break out hist trigger assignment parsing Tom Zanussi
2017-06-26 22:49 ` [PATCH 09/32] tracing: Make traceprobe parsing code reusable Tom Zanussi
2017-06-26 22:49 ` [PATCH 10/32] tracing: Add NO_DISCARD event file flag Tom Zanussi
2017-06-26 22:49 ` [PATCH 11/32] tracing: Add post-trigger flag to hist trigger command Tom Zanussi
2017-06-26 22:49 ` [PATCH 12/32] tracing: Add hist trigger timestamp support Tom Zanussi
2017-07-17  6:00   ` Namhyung Kim
2017-07-17 16:57     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 13/32] tracing: Add per-element variable support to tracing_map Tom Zanussi
2017-06-26 22:49 ` [PATCH 14/32] tracing: Add hist_data member to hist_field Tom Zanussi
2017-06-26 22:49 ` [PATCH 15/32] tracing: Add usecs modifier for hist trigger timestamps Tom Zanussi
2017-06-26 22:49 ` [PATCH 16/32] tracing: Add variable support to hist triggers Tom Zanussi
2017-07-19  1:07   ` Namhyung Kim [this message]
2017-07-19 15:40     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 17/32] tracing: Account for variables in named trigger compatibility Tom Zanussi
2017-06-26 22:49 ` [PATCH 18/32] tracing: Add simple expression support to hist triggers Tom Zanussi
2017-07-21  2:02   ` Namhyung Kim
2017-07-21 16:29     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 19/32] tracing: Add variable reference handling " Tom Zanussi
2017-07-21  3:31   ` Namhyung Kim
2017-07-21 16:41     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 20/32] tracing: Add support for dynamic tracepoints Tom Zanussi
2017-06-26 22:49 ` [PATCH 21/32] tracing: Add hist trigger action hook Tom Zanussi
2017-06-26 22:49 ` [PATCH 22/32] tracing: Add support for 'synthetic' events Tom Zanussi
2017-07-23 12:00   ` Namhyung Kim
2017-07-24 16:11     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 23/32] tracing: Add 'onmatch' hist trigger action support Tom Zanussi
2017-07-23 15:12   ` Namhyung Kim
2017-07-24 16:17     ` Tom Zanussi
2017-07-26  2:40   ` Namhyung Kim
2017-07-26 16:38     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 24/32] tracing: Add 'onmax' " Tom Zanussi
2017-07-26  3:04   ` Namhyung Kim
2017-07-26 16:45     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 25/32] tracing: Allow whitespace to surround hist trigger filter Tom Zanussi
2017-06-26 22:49 ` [PATCH 26/32] tracing: Make duplicate count from tracing_map available Tom Zanussi
2017-06-26 22:49 ` [PATCH 27/32] tracing: Add cpu field for hist triggers Tom Zanussi
2017-06-26 22:49 ` [PATCH 28/32] tracing: Add hist trigger support for variable reference aliases Tom Zanussi
2017-06-26 22:49 ` [PATCH 29/32] tracing: Add 'last error' error facility for hist triggers Tom Zanussi
2017-07-26  4:39   ` Namhyung Kim
2017-07-26 16:47     ` Tom Zanussi
2017-06-26 22:49 ` [PATCH 30/32] tracing: Add inter-event hist trigger Documentation Tom Zanussi
2017-06-26 22:49 ` [PATCH 31/32] tracing: Make tracing_set_clock() non-static Tom Zanussi
2017-06-26 22:49 ` [PATCH 32/32] tracing: Add a clock attribute for hist triggers Tom Zanussi
2017-06-27 14:58 ` [PATCH 00/32] tracing: Inter-event (e.g. latency) support Steven Rostedt
2017-06-28 14:21 ` Masami Hiramatsu
2017-06-28 19:09   ` Tom Zanussi
2017-07-01  7:01 ` Joel Fernandes (Google)
2017-07-12 19:17   ` Tom Zanussi
2017-07-04 16:12 ` Sebastian Andrzej Siewior
2017-07-12 19:20   ` Tom Zanussi

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