On Fri, Jun 17, 2022 at 07:10:01PM -0000, Daan De Meyer via devel wrote:
> Regressions of such magnitude can veto such changes, especially
when
> they hit everyone, not just those who are highly dependent on the
> profiling tools the proposal is concerned about.
The kernel benchmarks were added as an example of openly available data we could find on
the potential impact of frame pointers. Note that the email from Mel Gorman is all we have
to go on. Unfortunately the original data from the benchmarks is gone so I can't try
to reproduce them. I've emailed Mel to see if he still has the benchmarks stored
somewhere so we can perhaps try to reproduce the results.
I've added a clarification to the change proposal that we don't intend to
actually compile the kernel with frame pointers
OK, so the (old!) kernel benchmarks are not of little relevance.
I think that this really needs to be benchmarked. Without that the
discussion will just go on in circles. There are two nice options for
this: either copr, where you first build the redhat-rpm-config with the
adjusted options and then rebuild some subset of rawhide to be able
to do benchmarks, or just the same thing locally on a server with a bunch
of CPUs. One architecture should be enough. Mini-rebuilds like that take
a few days, so it's entirely possible to do.
Zbyszek