On Wed, Jan 31, 2018 at 12:48 PM, Nadav Amit <[email protected]> wrote: > Andy Lutomirski <[email protected]> wrote: > >> >> >>> On Jan 31, 2018, at 12:11 PM, Nadav Amit <[email protected]> wrote: >>> >>> The TLB invalidation info is allocated on the stack, which might cause >>> it to be unaligned. Since this information may be transferred to >>> different cores for TLB shootdown, this might result in an additional >>> cache-line bouncing between the cores. >>> >>> GCC provides a way to deal with it by using >>> __builtin_alloca_with_align(). Use it to avoid the bouncing cache lines. >> >> Eww. How about __aligned? > > Err.. Stupid me. For some reason I remembered I tried it and it didn’t have > the desired effect, which caused me to assume it does not work for variables > on the stack. Anyhow, it does the work. I’ll submit v2. >
You're probably remembering that __aligned(16) malfunctions on older GCC versions. But __aligned(64), which is what you want, has always been okay AFAIK.
