[PATCH v2 0/2] ftrace: Add timer-source of walltime for ftrace

[Zhaolei <zhaolei@cn.fujitsu.com>]

Hi,

I rebased patchset of "enable ftrace display walltime".

It can make ftrace display intuitionistic time information to user
with walltime clock.

We can get following output by using it:
 # cd /mnt/debugfs/tracing/
 # cat trace_clock
 [local] global walltime
 # echo sched_switch > current_tracer
 # cat trace
 # tracer: sched_switch
 #
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
             bash-3580  [000]  2916.188093:   3580:120:S   + [000]  3580:120:S bash
             bash-3580  [000]  2916.188205:   3580:120:S   + [000]  3580:120:S bash
             bash-3580  [000]  2916.188538:   3580:120:R   + [000]     5:115:S events/0
             bash-3580  [000]  2916.188599:   3580:120:R ==> [000]     5:115:R events/0
         events/0-5     [000]  2916.188669:      5:115:S ==> [000]  3580:120:R bash
 ...
 # echo walltime > trace_clock
 # cat trace
 # tracer: sched_switch
 #
 #           TASK-PID    CPU#           TIMESTAMP  FUNCTION
 #              | |       |                        |         |
             bash-3580  [000] 2009-08-24 18:03:16.500705:   3580:120:S   + [000]  3580:120:S bash
             bash-3580  [000] 2009-08-24 18:03:16.500815:   3580:120:S   + [000]  3580:120:S bash
             bash-3580  [000] 2009-08-24 18:03:16.500815:   3580:120:S   + [000]  3580:120:S bash
             bash-3580  [000] 2009-08-24 18:03:16.500815:   3580:120:S ==> [000]     5:115:R events/0
         events/0-5     [000] 2009-08-24 18:03:16.500815:      5:115:R   + [000]  3578:120:S sshd
 ...

It need to applys on my patch of:
[PATCH v4 1/2] Add function to convert between calendar time and broken-down time for universal use

Hi, Thomas,

To make ftrace's walltime function work, I need to add a tracepoint into xtime's code,
so we can set ftrace's walltime clockbase when time changed.

Could you have a look at this patch, and give me your suggestion?

Changelog:
v1->v2: Rebase to top of tip tree.

Thanks
Zhaolei