Ingo Molnar <[EMAIL PROTECTED]> wrote: > the question is: which is more important, the type safety of a > container_of() [or type cast], which if we get it wrong produces a > /very/ trivial crash that is trivial to fix - or embedded timers data > structure size all around the kernel? I believe the latter is more > important.
Indeed yes. Using container_of() and ditching the data value, you generally have to have one extra instruction per timer handler, if that, but you are able to discard one instruction or more from __run_timers() and struct timer_list discards a word. You will almost certainly have far more timer_list structs in the kernel than timer handler functions, therefore it's a space win, and possibly also a time win (if the reduction of __run_timers() is greater than the increase in the timer handler). And that extra instruction in the timer handler is usually going to be an addition or subtraction of a small immediate value - which may be zero (in which case the insn is dropped) or which may be folded directly into memory access instruction offsets. David - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
