On 11/10/22 08:59, Michael Catanzaro wrote:
On Wed, Nov 9 2022 at 09:39:04 AM +0100, Vitaly Zaitsev via devel
<devel(a)lists.fedoraproject.org> wrote:
> According to tests, this will slow down your system to 2.5%+, which is
> unacceptable for a general purpose distribution.
Of course, without the frame pointers, profiling software is impossible
and performance engineers are unable to investigate performance
problems using Fedora. Seems kind of silly to block performance work
just for a 2.5% benefit....
Michael
Have you considered submitting kernel patches for DWARF unwinding? The
actual unwinding can be done in the vdso, so bugs do not crash the kernel.
That eliminates the main reason for Linus’s objection IIUC. It does mean
that user stack unwinding needs to move from NMI context to just before
system call return, but that is a good thing anyway as it allows faulting
in stack pages if needed.
--
Sincerely,
Demi Marie Obenour (she/her/hers)