linux-kernel - Re: [RFC][PATCH] ftrace interface for blktrace

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Date:	Fri, 16 Jan 2009 14:15:55 -0500 (EST)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>
cc:	Jens Axboe <jens.axboe@...cle.com>, Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] ftrace interface for blktrace


Arnaldo,

Cool stuff!

On Fri, 16 Jan 2009, Arnaldo Carvalho de Melo wrote:

> Hi Jens,
> 
> 	The patch below adds a ftrace interface for blktrace, allowing
> people to use it without any required userspace tools, using sysfs to setup the
> act_mask, pid, start_lba, end_lba.
> 
> 	Example usage:
> 
> [root@...-1 ~]# mount -t debugfs none /sys/kernel/debug/

I think you are the only person that mounts debugfs on the "official"
location ;-)

> [root@...-1 ~]# ls /sys/block/sda/sda1/trace/
> act_mask  enable  end_lba  pid  start_lba
> [root@...-1 ~]# cat /sys/kernel/debug/tracing/available_tracers 
> blk function_graph wakeup function sched_switch nop
> [root@...-1 ~]# echo blk > /sys/kernel/debug/tracing/current_tracer 

You must like to type.

-- Steve

> [root@...-1 ~]# cat /sys/kernel/debug/tracing/trace
> # tracer: blk
> #
> # DEV   CPU TIMESTAMP     PID ACT FLG
> #  |     |     |           |   |   |
> [root@...-1 ~]# echo 1 > /sys/block/sda/sda1/trace/enable 
> [root@...-1 ~]# tail /sys/kernel/debug/tracing/trace
>   8,1    0   143.070085  1208  P  NS [tail]
>   8,1    0   143.070087  1208  I RBS 4154375 + 8 [tail]
>   8,1    0   143.070091  1208  A WBS 4155391 + 16 <- (8,1) 4155328
>   8,1    0   143.070091  1208  Q   R 4155391 + 16 [tail]
>   8,1    0   143.070094  1208  G  RB 4155391 + 16 [tail]
>   8,1    0   143.070094  1208  I RBS 4155391 + 16 [tail]
>   8,1    0   143.070097  1208  U  WS [tail] 2
>   8,1    0   143.070101  1208  D  WB 4154375 + 8 [tail]
>   8,1    0   143.070341  1208  D  WB 4155391 + 16 [tail]
>   8,1    0   143.070635     0  C  RS 4154375 + 8 [0]
> [root@...-1 ~]#
> 
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