On Thu, Oct 24, 2019 at 09:41:22AM -0500, Jeremy Linton wrote: > Hi, > > On 8/22/19 11:36 AM, Laura Abbott wrote: > > On 8/22/19 8:58 AM, Prarit Bhargava wrote: > > > On 8/19/19 9:15 AM, Laura Abbott wrote: > > > > On 8/16/19 2:57 PM, Paul Bolle wrote: > > > > > Florian Weimer schreef op vr 16-08-2019 om 14:04 [+0200]: > > > > > > RHEL has a larger NR_CPU value, though. For example, it's 8192 on > > > > > > x86-64, while Fedora 31 has 1024. > > > > > > > > > > On the Fedora x86-64 debug builds it's 8192 again. Why's that? > > > > > > > > > > > > > > > Paul Bolle > > > > > > > > > > > > > That's the option for max cpus. We don't want to turn it on in all > > > > Fedora builds since it would use up more resources we probably don't > > > > actually need. Turning on for debugging in Fedora is okay though. > > > > RHEL is focused on larger footprints and makes the trade off to > > > > have it enabled all the time. > > > > > > > > > > I think I measured the impact of 8192 vs 512 (or 256?) a long time > > > ago and we > > > are talking about _k_ of memory. We should stick with what upstream > > > has at > > > 8192. It's easier to debug when we have the same value as the > > > default IMO. > > > > > > Having said that, it has been a long time since I had to debug a > > > NR_CPUS/nr_cpus > > > issue in the kernel. We're just not seeing bugs around the value > > > anymore. > > > > > > > I was going to ask about the actual impact of a larger number of CPUs. > > If it's > > actually only k of memory it's probably better to just set MAXCPUS all > > the time. > > Even the lowest end machines probably see more change when frameworks > > change. > > > > And yes, I also think that we've come a long way so NR_CPUS is less of > > an important > > option to optimize these days. I think I'll just submit another patch to > > just do > > the max cpus. > > > > Forgive me if you have already posted (didn't see it yet). > > Its probably a good idea to bump the aarch64 config at the same time. Some > aarch64 "desktop" machines is already at the 256 core limit currently in > use. > I've bumped aarch64 up to 4096, s390x up to 512, and powerpc up to 2048 in Rawhide and it'll be in the build after v5.4-rc6. - Jeremy _______________________________________________ kernel mailing list -- kernel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to kernel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/kernel@xxxxxxxxxxxxxxxxxxxxxxx
