Re: [PATCH] perf record: Set timestamp boundary for AUX area events

From: Adrian Hunter
Date: Mon May 03 2021 - 11:06:22 EST


On 3/05/21 5:56 pm, Andi Kleen wrote:
> On Mon, May 03, 2021 at 09:42:22AM +0300, Adrian Hunter wrote:
>> AUX area data is not processed by 'perf record' and consequently the
>> --timestamp-boundary option may result in no values for "time of first
>> sample" and "time of last sample". However there are non-sample events
>> that can be used instead, namely 'itrace_start' and 'aux'.

"instead" -> "as well"

>> 'itrace_start' is issued before tracing starts, and 'aux' is issued
>> every time data is ready.
>
> Hmm, what happens when some other non PT events are in the same perf record?

The sample timestamps are still processed, so the lowest sample timestamp or
'itrace_start' timestamp or 'aux' timestamp is the start. Similarly for the end.

> And those maybe run at different times than PT (e.g. due to some PT specific
> filter). Does this all work correctly then?

The broadest range is used