On Fri, 2008-06-06 at 16:15 -0400, Pavel Roskin wrote: > On Fri, 2008-06-06 at 11:47 -0700, Harvey Harrison wrote: > > > unlikely() isn't some magic make-me-faster function, it just moves code > > to the end of the function to get it out of the icache and jumps to it > > in the unlikely case it is taken. When all there is is a return, I > > don't think it even makes any difference. In both these cases a comment > > is probably more appropriate. > > If we don't more return to the end, we get something like: > > compare skb->len to 10 > if more or equal goto 1 > return > 1: <the likely case> > > I don't know much about modern processor design, but I remember reading > that even a very short jump would flush the instruction pipeline and > cause some delay. > > I would keep unlikely() and let the compiler think what to do with it. > On X86-32 at least the generated code is exactly the same with or without the unlikely()s. I'll put them back in a follow-on if people are really attached to them. Harvey -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
