On Thu, Feb 01, 2007 at 01:02:41PM +0100, Andi Kleen wrote: > I don't think so because having per process state in a vsyscall > is quite costly. You would need to allocate at least one more > page to each process, which I think would be excessive.
You would need one page per cpu and to check a change in a TIF_ bitflag during switch_to (zero cost) and overwrite the vsyscall bit in the slow path. If we had a picotimeofday that would be guaranteed monotone... if he can measure errors with shared memory in smp, it means the measurement error (LAPIC and tsc frequency estimation) is longer than the time it takes to bounce a spinlock and reach a second rdtscp. I hoped this wouldn't happen. Could you send me the app used to reproduce the non-monotonicity over shared memory with rdtscp? I finally have a (EE) stepping F to attempt testing it. thanks! - 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/
