On Thu, Feb 11, 2021 at 1:03 PM Ondrej Mosnacek <omosnace@xxxxxxxxxx> wrote: > > On Thu, Feb 11, 2021 at 10:14 AM Viktor Ashirov <vashirov@xxxxxxxxxx> wrote: > > On Wed, Feb 3, 2021 at 5:54 PM Michael Catanzaro <mcatanzaro@xxxxxxxxx> wrote: > >> > >> Hi, > >> > >> Has anybody investigated Jim Salter's claims that Fedora 32 is slow to > >> launch applications? Recent article: > >> > >> https://arstechnica.com/gadgets/2021/02/ubuntu-core-20-adds-secure-boot-with-hardware-backed-encryption/ > >> > >> "in my experience, Fedora 32 is noticeably, demonstrably more sluggish > >> to launch applications than Ubuntu is in general." > >> > >> Original article: > >> > >> https://arstechnica.com/gadgets/2020/05/linux-distro-review-fedora-workstation-32/ > >> > >> Would be good to know, for starters, whether this difference is real > >> and measurable. > > > > This was bugging me for a while. I also noticed that Fedora 32 is a bit slower than it used to be. Compilation time of a project that I'm working on went from ~35-36 seconds to ~47-48. At first I thought that it's just another round of CPU vulnerabilities mitigations that introduced a performance drop. But after some digging I found that the default CPU governor was switched from 'ondemand' to 'schedutil' in Fedora kernel 5.9.7: > > https://src.fedoraproject.org/rpms/kernel/c/73c86ebaee23df8310b903c1dab2176d443f5a3a?branch=rawhide > > (see configs/fedora/generic/CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL) > > > > I switched it back using cpupower from kernel-tools: > > $ sudo cpupower frequency-set --governor ondemand > > > > And confirmed that my compilation time went back to the previous ~35 seconds. > > In the end I switched the governor to 'performance' and shaved another 5 seconds. And gnome-shell no longer feels sluggish, switching tabs in the browser is also instant. > > To make the change permanent I used settings in /etc/sysconfig/cpupower and enabled cpupower service: > > $ sudo systemctl enable --now cpupower.service > > > > The change of the default CPU governor looks pretty significant to me, but I couldn't find any discussions about it. > > CCing the Fedora kernel list and Justin. At the ARK tree level, the > change was introduced in this commit, with no explanation: > https://gitlab.com/cki-project/kernel-ark/commit/9d69ad49ab90db607e25a99eacbf31dc9e513dfa > > Justin, do you remember the reason for the change? Can/should it be reverted? It was upstream changes, the Intel maintainer changed it in [1] if X86_INTEL_PSTATE state was selected in late March which would make sense in the timg, and also changed for arm arches [2] in July. If that change was made upstream I'm assuming it was assumed that performance should be equivalent or better than the other option, I suspect we should engage with upstream as they're probably interested in the issues. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a00ec3874e7d3 [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f259eab3ea0e7 _______________________________________________ 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 Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
