From: Eric Dumazet <[EMAIL PROTECTED]> Date: Mon, 01 Oct 2007 07:59:12 +0200
> No problem here on bigger servers, so I CC David Miller and netdev > on this one. AFAIK do_gettimeofday() and ktime_get_real() should > use the same underlying hardware functions on PC and no performance > problem should happen here. One thing that jumps out at me is that on 32-bit (and to a certain extent on 64-bit) there is a lot of stack accesses and missed optimizations because all of the work occurs, and gets expanded, inside of ktime_get_real(). The timespec_to_ktime() inside of there constructs the ktime_t return value on the stack, then returns that as an aggregate to the caller. That cannot be without some cost. ktime_get_real() is definitely a candidate for inlining especially in these kinds of cases where we'll happily get computations in local registers instead of all of this on-stack nonsense. And in several cases (if the caller only needs the tv_sec value, for example) computations can be elided entirely. It would be constructive to experiment and see if this is in fact part of the problem. - 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/
