On 30/01/2015 16:14, Radim Krčmář wrote: > > > + case KVM_APIC_MODE_XAPIC_FLAT: > > > + *cid = 0; > > > + *lid = ldr & 0xff; > > > + return true; > > > + case KVM_APIC_MODE_XAPIC_CLUSTER: > > > + *cid = (ldr >> 4) & 0xf; > > > + *lid = ldr & 0xf; > > > + return true; > > > + case KVM_APIC_MODE_X2APIC: > > > + *cid = ldr >> 16; > > > + *lid = ldr & 0xffff; > > > + return true; > > > + } > >> > lid_bits = mode; >> > cid_bits = mode & (16 | 4); >> > lid_mask = (1 << lid_bits) - 1; >> > cid_mask = (1 << cid_bits) - 1; >> > >> > *cid = (ldr >> lid_bits) & cid_mask; >> > *lid = ldr & lid_mask; > Would jump predictor fail on the switch? Or is size of the code that > important? This code is shorter, but is going to execute far more > operations, so I think it would be slower ... (And harder to read.)
Considering the additional comparisons for the switch, I don't think it's going to execute far more operations... Paolo -- 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/
