[BUG] perf record: GROUP_DESC not supported in pipe mode

[Stephane Eranian]

Hi,

I ran into a problem trying to group events in perf record while in pipe mode.
If I do:


$ perf record --group -e '{cycles, instructions}' -o - | perf report
-i - --group

I do not get the profiles grouped together. Instead I get two profiles.

Looking at the code in util/header.c I see that a bunch of features and not
supported in pipe mode (synthesized method). It is not clear to me why.
Clearly grouping should be supported. This is a very commonly used mode.

Am I missing something?
Thanks.