On Thu, Feb 11, 2021 at 1:03 PM Ondrej Mosnacek omosnace@redhat.com wrote:
On Thu, Feb 11, 2021 at 10:14 AM Viktor Ashirov vashirov@redhat.com wrote:
On Wed, Feb 3, 2021 at 5:54 PM Michael Catanzaro mcatanzaro@gnome.org 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...
"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-workstati...
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/73c86ebaee23df8310b903c1dab2176d... (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/9d69ad49ab90db607e25a99eacb...
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/?i... [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...