On Tue, 12 Dec 2023 at 13:06, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > On Tue, Dec 12, 2023 at 03:50:25PM +0800, Gao Xiang wrote: > > I have no idea how it's faster than the current initramfs or initrd. > > So if it's really useful, maybe some numbers can be posted first > > with the current `memmap` hack and see it's worth going further with > > some new infrastructure like initdax. > > Agreed. > I was politely poked this morning to highlight the graphs on the initoverlayfs page, so as promised highlighting. That's not to say this is either kernelspace's or userspace's role to optimize, but it does prove there are benefits if we put some effort into optimizing early boot. https://github.com/containers/initoverlayfs With this approach systemd starts ~300ms faster on a Raspberry Pi 4 with sd card, and this systemd instance has access to all the files that a traditional initramfs would. I did this test on a Raspberry Pi 4 with NVMe drive over USB and the results were closer to a 500ms benefit in systemd start time. Is mise le meas/Regards, Eric Curtin
