On Thu, 17 Mar 2011, Eric Dumazet wrote: > By the way, I noticed : > > DECLARE_PER_CPU(u64, xt_u64); > __this_cpu_add(xt_u64, 2) translates to following x86_32 code : > > mov $xt_u64,%eax > add %fs:0x0,%eax > addl $0x2,(%eax) > adcl $0x0,0x4(%eax) > > > I wonder why we dont use : > > addl $0x2,%fs:xt_u64 > addcl $0x0,%fs:xt_u64+4 The compiler is fed the following *__this_cpu_ptr(xt_u64) += 2 __this_cpu_ptr makes it: *(xt_u64 + __my_cpu_offset) += 2 So the compiler calculates the address first and then increments it. The compiler could optimize this I think. Wonder why that does not happen. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
