On Thu, Mar 10, 2022 at 9:37 AM Justin Pryzby <pryzby@telsasoft.com> wrote:
> On Wed, Mar 09, 2022 at 10:12:54AM -0800, Andres Freund wrote:
> > On 2022-03-09 11:47:23 -0600, Justin Pryzby wrote:
> > > I'm curious what you think of this patch.
> > >
> > > It makes check-world on freebsd over 30% faster - saving 5min.
> >
> > That's nice! While -Og makes interactive debugging noticeably harder IME, it's
> > not likely to be a large enough difference just for backtraces etc.
>
> Yeah. gcc(1) claims that -Og can improve debugging.
Wow, I see the effect on Cirrus -- test_world ran in 8:55 instead of
12:43 when I tried (terrible absolute times, but fantastic
improvement!). Hmm, on my local FreeBSD 13 box I saw 5:07 -> 5:03
with this change. My working theory had been that there is something
bad happening in the I/O stack under concurrency making FreeBSD on
Cirrus/GCP very slow (ie patterns to stall on slow cloud I/O waits,
something I hope to dig into when post-freeze round tuits present
themselves), but that doesn't gel with this huge improvement from
noodling with optimiser details, and I don't know why I don't see
something similar locally. I'm confused.
Just BTW it's kinda funny that we say -ggdb for macOS and then we use
lldb to debug cores in cores_backtrace.sh. I suppose it would be more
correct to say -glldb, but doubt it matters much...
