On 11/01/2017 10:47 AM, Karel Zak wrote:
> On Tue, Oct 31, 2017 at 08:01:31AM -0400, Prarit Bhargava wrote:
>> The kernel outputs multi-line messages (kernel messages that contain
>> the end-of-line character '\n'). These message are currently displayed by
>> dmesg as
>>
>> [965199.028940] runnable tasks:
>> task PID tree-key switches prio
>> wait-time sum-exec sum-sleep
>> ----------------------------------------------------------------------------------------------------------
>>
>> The kernel timestamps each of these lines with [965199.028940] and the
>> dmesg utility should do the same.
>>
>> Add the 'force-prefix'/'-p' dmesg option to add decode & timestamp information
>> to each line of a multi-line message.
>>
>> Notes: The new print_record() algorithm stores the decode & timestamp
>> information in buffers. If the force-prefix option is used, the message is
>> split into separate lines and each line is prefixed with the stored decode &
>> timestamp information. The splitting of the message into separate lines is
>> done using strtok() which requires write access to the message buffer (ie, the
>> const message buffer is now copied into a writeable buffer).
>>
>> Successfully tested by me by looking at sysrq-t and sysrq-w output.
>> All known good /tests passed with these changes.
>
> Merged with some changes:
>
> - use snprintf()
> - cleanup \n usage (don't count line break to the
> message text in the parsers and always print \n after the text
> - add the option to the man page
> - use --force-prefix for kmsg only, old syslog(2) API splits messages itself
> - strdup() the message text only on force-prefix
>
> Please, test it again :-)
>
Done :) and IMO the tests pass.
Note that there are 3 tests/ that that fail before and after my patch.
I tested and old and new dmesg using alt-sysrq-w.
The kernel console displays
<snip>
[101640.296136] .rt_throttled : 0
[101640.301374] .rt_time : 0.000000
[101640.307288] .rt_runtime : 950.000000
[101640.313396]
[101640.313396] runnable tasks:
[101640.313396] task PID tree-key switches prio
wait-time sum-exec sum-sleep
[101640.313396]
----------------------------------------------------------------------------------------------------------
<snip>
and old dmesg shows
[101640.296136] .rt_throttled : 0
[101640.301374] .rt_time : 0.000000
[101640.307288] .rt_runtime : 950.000000
[101640.313396]
runnable tasks:
task PID tree-key switches prio wait-time
sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
The new dmesg (no additional options) shows
[101640.296136] .rt_throttled : 0
[101640.301374] .rt_time : 0.000000
[101640.307288] .rt_runtime : 950.000000
[101640.313396]
runnable tasks:
task PID tree-key switches prio
wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
which provides backwards compatibility with the old dmesg behavior
The new dmesg with --force-prefix shows
[101640.296136] .rt_throttled : 0
[101640.301374] .rt_time : 0.000000
[101640.307288] .rt_runtime : 950.000000
[101640.313396] runnable tasks:
[101640.313396] task PID tree-key switches prio
wait-time sum-exec sum-sleep
[101640.313396]
----------------------------------------------------------------------------------------------------------
The new dmesg with --force-prefix -e shows
[ +0.005237] .rt_throttled : 0
[ +0.005238] .rt_time : 0.000000
[ +0.005914] .rt_runtime : 950.000000
[ +0.006108] runnable tasks:
[ +0.000000] task PID tree-key switches prio
wait-time sum-exec sum-sleep
[ +0.000000]
----------------------------------------------------------------------------------------------------------
The new dmesg with --force-prefix -x shows
kern :warn : [101640.301374] .rt_time : 0.000000
kern :warn : [101640.307288] .rt_runtime : 950.000000
kern :warn : [101640.313396] runnable tasks:
kern :warn : [101640.313396] task PID tree-key switches
prio wait-time sum-exec sum-sleep
kern :warn : [101640.313396]
----------------------------------------------------------------------------------------------------------
So I think it works! :)
P.
> Karel
>
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