On 27/02/25 18:35, Mark Rutland wrote: > On Thu, Feb 27, 2025 at 07:08:56PM +0100, Valentin Schneider wrote: >> On 13/02/25 21:00, Jinjie Ruan wrote: >> > Currently, x86, Riscv, Loongarch use the generic entry. Convert arm64 >> > to use the generic entry infrastructure from kernel/entry/*. >> > The generic entry makes maintainers' work easier and codes >> > more elegant. >> > >> > Switch arm64 to generic IRQ entry first, which removed duplicate 100+ >> > LOC and make Lazy preemption on arm64 available by adding a >> > _TIF_NEED_RESCHED_LAZY bit and enabling ARCH_HAS_PREEMPT_LAZY. >> >> Just a drive-by comment as I'm interested in lazy preemption for arm64; >> this series doesn't actually enable lazy preemption, is that for a >> follow-up with the rest of the generic entry stuff? >> >> From a quick glance, it looks like everything is in place for enabling it. > > Sorry, there's been some fractured discussion on this on the > linux-rt-users list: > > > https://lore.kernel.org/linux-rt-users/20241216190451.1c619...@mordecai.tesarici.cz/ > > The TL;DR is that lazy preemption doesn't actually depend on generic > entry, and we should be able to enable it on arm64 independently of this > series. I'd posted a quick hack which Mike Galbraith cleaned up: > > > https://lore.kernel.org/linux-rt-users/a198a7dd9076f97b89d8882bb249b3bf303564ef.ca...@gmx.de/ > > ... but that was never posted as a new thread to LAKML. >
Thanks for the breadcrumbs! > Would you be happy to take charge and take that patch, test it, and post > it here (or spin your own working version)? I was happy with the way it > looks but hadn't had the time for testing and so on. > Sure, looks straightforward enough, I'll pick this up. > I expect that we'll merge the generic entry code too, but having them > separate is a bit easier for bisection and backporting where people want > lazy preemption in downstream trees. > > Mark.
