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SubjectRe: [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@f10-1 ~]# mount -t debugfs none /sys/kernel/debug/

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

> [root@f10-1 ~]# ls /sys/block/sda/sda1/trace/
> act_mask enable end_lba pid start_lba
> [root@f10-1 ~]# cat /sys/kernel/debug/tracing/available_tracers
> blk function_graph wakeup function sched_switch nop
> [root@f10-1 ~]# echo blk > /sys/kernel/debug/tracing/current_tracer

You must like to type.

-- Steve

> [root@f10-1 ~]# cat /sys/kernel/debug/tracing/trace
> # tracer: blk
> #
> # DEV CPU TIMESTAMP PID ACT FLG
> # | | | | | |
> [root@f10-1 ~]# echo 1 > /sys/block/sda/sda1/trace/enable
> [root@f10-1 ~]# 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@f10-1 ~]#
>


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