Re: [PATCH] printk: Add caller information to printk() output.

[Tetsuo Handa]

On 2018/12/05 0:27, Petr Mladek wrote:
> On Tue 2018-12-04 06:10:40, Tetsuo Handa wrote:
>> On 2018/12/04 0:06, Petr Mladek wrote:
>>>> If we modify print_time(), I think that the leading spaces inserted by "%5lu"
>>>> makes little sense, for "%5lu" is too small for systems with uptime >= 1.16 days
>>>> and parsers after all cannot assume fixed length for the timestamp field. Then,
>>>> we could change from "%5lu.%06lu" to "%lu.%06lu" so that parsers (like /bin/awk)
>>>> can get prefix part using white spaces as a delimiter.
>>>
>>> My primary concern was a human readability. The different header columns
>>> are separated by brackets and the message itself is separated by the space.
>>
>> PID_MAX_LIMIT is 4194304, which can take up to 10 bytes if [T%u] is used.
> 
> 4194304 is the worst case. I would use the same approach as with the
> timestamp seconds. It uses 5 characters as the minimum. But it might
> eventully get bigger.
> 
> IMHO, [T%5u] looks like a reasonable default.
> 

While "%5lu.%06lu" for uptime does not decrease over time (and hence changing
to "%lu.%06lu" does not cause wavy output), "[%6s]" for T$thread_id will cause
wavy output after PID reached 100000. Isn't it hard to parse after all?