Re: [GIT pull] printk updates for 4.15

[Sergey Senozhatsky]

Hello Mark,

On (11/14/17 07:56), Mark Salyzyn wrote:
[..]
> Thanks for the vote of confidence :-) but we were holding back re spinning
> that set until the ability to switch the primary timestamp got accepted. (we
> were to use U suffix for realtime, B for boottime etc to designate them).
> 
> Printing the other timebases during major disruptions (suspend/resume/etc)
> was needed for our battery monitoring analysis tools, and we only used them
> as synchronization markers as a secondary effect.
> 
> But we _also_ had Android partners asking if it was possible to switch the
> primary (dmesg) timestamp to one of boottime or realtime to aid in triaging
> temporal issues. Doing so in the tool was sometimes too inaccurate
> (~+/-20ms) even with help sniffing the periodic synchronization/disruption
> prints. Switching the timebase for dmesg gave us roughly 1000 times more
> comparative time precision which helps immensely when trying to correlate
> and order the sequence of events in user space and kernel activities.

have you considered trace points?

	-ss