2015-01-30 16:10+0100, Paolo Bonzini: > On 30/01/2015 15:56, Radim Krčmář wrote: > > Do you know of a difference with it? > > new->mode & (new->mode - 1) | hweight8(new->mode) != 1 > > lea -0x1(%rax),%edi | popcnt %edi,%eax > > test %eax,%edi | cmp $1,%eax > > x & (x - 1) is really hweight8(new->mode) > 1. So if new->mode == 0 it > would have a different result.
(I was thinking if execution profile of those two instructions isn't vastly different. ">" in this check works too ... later it seemed like it was pushing lucky coincidence too far, so it ended as "!=" :) > >> Please add a comment to kvm_irq_delivery_to_apic_fast to explain what > >> you are doing. > > > > Would naming it kvm_apic_need_slow_delivery(), or something, be enough? > > Or kvm_apic_map_valid() perhaps? Sure, thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
