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SubjectRe: [PATCH 0/6] perf tools: Add wallclock time conversion support
On Thu, Jul 30, 2020 at 07:21:54PM -0600, David Ahern wrote:
> On 7/30/20 4:14 PM, peterz@infradead.org wrote:
> > On Thu, Jul 30, 2020 at 11:39:44PM +0200, Jiri Olsa wrote:
> >
> >> The patchset is adding the ability to display TOD/wallclock timestamp
> >> in 'perf script' output and in 'perf data convert --to-ctf' subcommand,
> >> so the converted CTF data contain TOD/wallclock timestamps.
> >
> > But why? Wallclock is a horrible piece of crap. Why would you want to do
> > this?
> >
>
> Same reason I brought this up 9+ years ago: userspace lives on
> time-of-day, and troubleshooting is based on correlating timestamps from
> multiple sources. To correlate a perf event to syslog or an application
> log, we need time-of-day.

You need a sync'ed CLOCK_MONOTONIC for that, CLOCK_REALTIME 'aka'
wallclock is a trainwreck, you don't ever want that.



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