On Fri, Mar 08, 2019 at 09:56:37PM +0100, Peter Zijlstra wrote: > Anyway, can anybody explain percpu_stable_op() vs percpu_from_op() ? > > I'm thinking of a variant of Linus' patch, but I'm confused about the > above.
So whatever I tried with +m only made things worse and always affects thousands of symbols. Now, afaict the whole percpu_stable_op thing is an ugly hack becaues some earlier compiler would not CSE the regular percpu_from_op. But since it does do that today; esp. after my first patch, I tried implementing this_cpu_read_stable() with percpu_from_op() (no volatile, obv). That also affects _lots_ of sites, but also significantly shrinks the kernel image. It's 2307 symbols affected, but: 17642871 2157438 747808 20548117 1398a15 defconfig-build1/vmlinux.o (patch 1) 17639081 2157438 747808 20544327 1397b47 defconfig-build0/vmlinux.o (patch 1 - percpu_stable_op) So I think I'll add a patch removing percpu_stable_op and all its users.
